diff --git a/pkg/apis/config/feature_flags.go b/pkg/apis/config/feature_flags.go
index 305200b7fe9..bcbfcdc4c1d 100644
--- a/pkg/apis/config/feature_flags.go
+++ b/pkg/apis/config/feature_flags.go
@@ -315,17 +315,17 @@ func NewFeatureFlagsFromConfigMap(config *corev1.ConfigMap) (*FeatureFlags, erro
 
 // EnableAlphaAPIFields enables alpha features in an existing context (for use in testing)
 func EnableAlphaAPIFields(ctx context.Context) context.Context {
-	return setEnableAPIFields(ctx, AlphaAPIFields)
+	return SetEnableAPIFields(ctx, AlphaAPIFields)
 }
 
 // EnableBetaAPIFields enables beta features in an existing context (for use in testing)
 func EnableBetaAPIFields(ctx context.Context) context.Context {
-	return setEnableAPIFields(ctx, BetaAPIFields)
+	return SetEnableAPIFields(ctx, BetaAPIFields)
 }
 
 // EnableStableAPIFields enables stable features in an existing context (for use in testing)
 func EnableStableAPIFields(ctx context.Context) context.Context {
-	return setEnableAPIFields(ctx, StableAPIFields)
+	return SetEnableAPIFields(ctx, StableAPIFields)
 }
 
 // CheckEnforceResourceVerificationMode returns true if the ResourceVerificationMode is EnforceResourceVerificationMode
@@ -348,7 +348,8 @@ func CheckAlphaOrBetaAPIFields(ctx context.Context) bool {
 	return cfg.FeatureFlags.EnableAPIFields == AlphaAPIFields || cfg.FeatureFlags.EnableAPIFields == BetaAPIFields
 }
 
-func setEnableAPIFields(ctx context.Context, want string) context.Context {
+// SetEnableAPIFields sets the config "enable-api-fields" to the "want" value
+func SetEnableAPIFields(ctx context.Context, want string) context.Context {
 	featureFlags, _ := NewFeatureFlagsFromMap(map[string]string{
 		"enable-api-fields": want,
 	})
diff --git a/pkg/apis/pipeline/v1/pipeline_validation.go b/pkg/apis/pipeline/v1/pipeline_validation.go
index 1c8ab05e6df..50569b24514 100644
--- a/pkg/apis/pipeline/v1/pipeline_validation.go
+++ b/pkg/apis/pipeline/v1/pipeline_validation.go
@@ -429,10 +429,6 @@ func validateResultsFromMatrixedPipelineTasksNotConsumed(tasks []PipelineTask, f
 // error is returned when the array indexing reference is out of bound of the array param
 // e.g. if a param reference of $(params.array-param[2]) and the array param is of length 2.
 func (ps *PipelineSpec) ValidateParamArrayIndex(ctx context.Context, params Params) error {
-	if !config.CheckAlphaOrBetaAPIFields(ctx) {
-		return nil
-	}
-
 	// Collect all array params lengths
 	arrayParamsLengths := ps.Params.extractParamArrayLengths()
 	for k, v := range params.extractParamArrayLengths() {
@@ -470,5 +466,10 @@ func (ps *PipelineSpec) ValidateParamArrayIndex(ctx context.Context, params Para
 		arrayIndexParamRefs = append(arrayIndexParamRefs, extractArrayIndexingParamRefs(p)...)
 	}
 
+	// if there are array indexing param references, the api feature gate needs to be set to `alpha` or `beta`
+	if len(arrayIndexParamRefs) > 0 && !config.CheckAlphaOrBetaAPIFields(ctx) {
+		return fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, arrayIndexParamRefs)
+	}
+
 	return validateOutofBoundArrayParams(arrayIndexParamRefs, arrayParamsLengths)
 }
diff --git a/pkg/apis/pipeline/v1/pipeline_validation_test.go b/pkg/apis/pipeline/v1/pipeline_validation_test.go
index a18e4f6025c..c3cdde68144 100644
--- a/pkg/apis/pipeline/v1/pipeline_validation_test.go
+++ b/pkg/apis/pipeline/v1/pipeline_validation_test.go
@@ -3339,14 +3339,11 @@ func getTaskSpec() TaskSpec {
 }
 
 func TestValidateParamArrayIndex_valid(t *testing.T) {
-	ctx := context.Background()
-	cfg := config.FromContextOrDefaults(ctx)
-	cfg.FeatureFlags.EnableAPIFields = config.BetaAPIFields
-	ctx = config.ToContext(ctx, cfg)
 	for _, tt := range []struct {
-		name     string
-		original PipelineSpec
-		params   []Param
+		name      string
+		original  PipelineSpec
+		params    []Param
+		apiFields string
 	}{{
 		name: "single parameter",
 		original: PipelineSpec{
@@ -3362,7 +3359,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "single parameter with when expression",
 		original: PipelineSpec{
@@ -3378,7 +3376,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				}},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "pipeline parameter nested inside task parameter",
 		original: PipelineSpec{
@@ -3393,7 +3392,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				},
 			}},
 		},
-		params: nil, // no parameter values.
+		params:    nil, // no parameter values.
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "array parameter",
 		original: PipelineSpec{
@@ -3411,6 +3411,7 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 		params: []Param{
 			{Name: "second-param", Value: *NewStructuredValues("second-value", "array")},
 		},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "parameter evaluation with final tasks",
 		original: PipelineSpec{
@@ -3430,7 +3431,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				}},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "parameter evaluation with both tasks and final tasks",
 		original: PipelineSpec{
@@ -3456,7 +3458,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				}},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "parameter references with bracket notation and special characters",
 		original: PipelineSpec{
@@ -3480,6 +3483,7 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 			{Name: "second/param", Value: *NewStructuredValues("second-value", "second-value-again")},
 			{Name: "fourth/param", Value: *NewStructuredValues("fourth-value", "fourth-value-again")},
 		},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "single parameter in workspace subpath",
 		original: PipelineSpec{
@@ -3501,10 +3505,29 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+	}, {
+		name: "validation with alpha gate",
+		original: PipelineSpec{
+			Params: []ParamSpec{
+				{Name: "first-param", Type: ParamTypeArray, Default: NewStructuredValues("default-value", "default-value-again")},
+				{Name: "second-param", Type: ParamTypeString},
+			},
+			Tasks: []PipelineTask{{
+				Params: []Param{
+					{Name: "first-task-first-param", Value: *NewStructuredValues("$(params.first-param[1])")},
+					{Name: "first-task-second-param", Value: *NewStructuredValues("$(params.second-param[0])")},
+					{Name: "first-task-third-param", Value: *NewStructuredValues("static value")},
+				},
+			}},
+		},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.AlphaAPIFields,
 	},
 	} {
 		tt := tt // capture range variable
+		ctx := config.SetEnableAPIFields(context.Background(), tt.apiFields)
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			err := tt.original.ValidateParamArrayIndex(ctx, tt.params)
@@ -3516,15 +3539,12 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 }
 
 func TestValidateParamArrayIndex_invalid(t *testing.T) {
-	ctx := context.Background()
-	cfg := config.FromContextOrDefaults(ctx)
-	cfg.FeatureFlags.EnableAPIFields = config.BetaAPIFields
-	ctx = config.ToContext(ctx, cfg)
 	for _, tt := range []struct {
-		name     string
-		original PipelineSpec
-		params   []Param
-		expected error
+		name      string
+		original  PipelineSpec
+		params    []Param
+		apiFields string
+		expected  error
 	}{{
 		name: "single parameter reference out of bound",
 		original: PipelineSpec{
@@ -3540,8 +3560,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "single parameter reference with when expression out of bound",
 		original: PipelineSpec{
@@ -3557,8 +3578,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				}},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "pipeline parameter reference nested inside task parameter out of bound",
 		original: PipelineSpec{
@@ -3573,8 +3595,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   nil, // no parameter values.
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    nil, // no parameter values.
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "array parameter reference out of bound",
 		original: PipelineSpec{
@@ -3592,7 +3615,8 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 		params: []Param{
 			{Name: "second-param", Value: *NewStructuredValues("second-value", "array")},
 		},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[3]) $(params.second-param[4])]"),
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[3]) $(params.second-param[4])]"),
 	}, {
 		name: "object parameter reference out of bound",
 		original: PipelineSpec{
@@ -3612,7 +3636,8 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 		params: []Param{
 			{Name: "second-param", Value: *NewStructuredValues("second-value", "array")},
 		},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[4]) $(params.second-param[4])]"),
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[4]) $(params.second-param[4])]"),
 	}, {
 		name: "parameter evaluation with final tasks reference out of bound",
 		original: PipelineSpec{
@@ -3632,8 +3657,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				}},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "parameter evaluation with both tasks and final tasks reference out of bound",
 		original: PipelineSpec{
@@ -3664,8 +3690,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 					}},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.first-param[3]) $(params.first-param[4]) $(params.second-param[2]) $(params.second-param[3]) $(params.second-param[4])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.first-param[3]) $(params.first-param[4]) $(params.second-param[2]) $(params.second-param[3]) $(params.second-param[4])]"),
 	}, {
 		name: "parameter in matrix reference out of bound",
 		original: PipelineSpec{
@@ -3682,8 +3709,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2])]"),
 	}, {
 		name: "parameter references with bracket notation and special characters reference out of bound",
 		original: PipelineSpec{
@@ -3707,7 +3735,8 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 			{Name: "second/param", Value: *NewStructuredValues("second-value", "second-value-again")},
 			{Name: "fourth/param", Value: *NewStructuredValues("fourth-value", "fourth-value-again")},
 		},
-		expected: fmt.Errorf("non-existent param references:[$(params[\"first.param\"][2]) $(params[\"second/param\"][2]) $(params['fourth/param'][2]) $(params['third.param'][2])]"),
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params[\"first.param\"][2]) $(params[\"second/param\"][2]) $(params['fourth/param'][2]) $(params['third.param'][2])]"),
 	}, {
 		name: "single parameter in workspace subpath reference out of bound",
 		original: PipelineSpec{
@@ -3729,13 +3758,57 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[3])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[3])]"),
+	}, {
+		name: "validation alpha feature gate",
+		original: PipelineSpec{
+			Params: []ParamSpec{
+				{Name: "first-param", Type: ParamTypeArray, Default: NewStructuredValues("default-value", "default-value-again")},
+				{Name: "second-param", Type: ParamTypeArray},
+			},
+			Tasks: []PipelineTask{{
+				Params: []Param{
+					{Name: "first-task-first-param", Value: *NewStructuredValues("$(params.first-param[2])")},
+					{Name: "first-task-second-param", Value: *NewStructuredValues("static value")},
+				},
+				Workspaces: []WorkspacePipelineTaskBinding{
+					{
+						Name:      "first-workspace",
+						Workspace: "first-workspace",
+						SubPath:   "$(params.second-param[3])",
+					},
+				},
+			}},
+		},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.AlphaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[3])]"),
+	}, {
+		name: "stable gate not allowed",
+		original: PipelineSpec{
+			Params: []ParamSpec{
+				{Name: "first-param", Type: ParamTypeArray, Default: NewStructuredValues("default-value", "default-value-again")},
+				{Name: "second-param", Type: ParamTypeString},
+			},
+			Tasks: []PipelineTask{{
+				Params: []Param{
+					{Name: "first-task-first-param", Value: *NewStructuredValues("$(params.first-param[2])")},
+					{Name: "first-task-second-param", Value: *NewStructuredValues("$(params.second-param[2])")},
+					{Name: "first-task-third-param", Value: *NewStructuredValues("static value")},
+				},
+			}},
+		},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.StableAPIFields,
+		expected:  fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, []string{"$(params.first-param[2])", "$(params.second-param[2])"}),
 	},
 	} {
 		tt := tt // capture range variable
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
+			ctx := config.SetEnableAPIFields(context.Background(), tt.apiFields)
 			err := tt.original.ValidateParamArrayIndex(ctx, tt.params)
 			if d := cmp.Diff(tt.expected.Error(), err.Error()); d != "" {
 				t.Errorf("ValidateParamArrayIndex() errors diff %s", diff.PrintWantGot(d))
diff --git a/pkg/apis/pipeline/v1/task_validation.go b/pkg/apis/pipeline/v1/task_validation.go
index fdf30e52dcb..94b291d78d6 100644
--- a/pkg/apis/pipeline/v1/task_validation.go
+++ b/pkg/apis/pipeline/v1/task_validation.go
@@ -607,11 +607,6 @@ func isParamRefs(s string) bool {
 // - `trParams` are params from taskrun.
 // - `taskSpec` contains params declarations.
 func (ts *TaskSpec) ValidateParamArrayIndex(ctx context.Context, params Params) error {
-	cfg := config.FromContextOrDefaults(ctx)
-	if cfg.FeatureFlags.EnableAPIFields != config.AlphaAPIFields {
-		return nil
-	}
-
 	// Collect all array params lengths
 	arrayParamsLengths := ts.Params.extractParamArrayLengths()
 	for k, v := range params.extractParamArrayLengths() {
@@ -634,5 +629,10 @@ func (ts *TaskSpec) ValidateParamArrayIndex(ctx context.Context, params Params)
 		arrayIndexParamRefs = append(arrayIndexParamRefs, extractArrayIndexingParamRefs(p)...)
 	}
 
+	// if there are array indexing param references, the api feature gate needs to be set to `alpha` or `beta`
+	if len(arrayIndexParamRefs) > 0 && !config.CheckAlphaOrBetaAPIFields(ctx) {
+		return fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, arrayIndexParamRefs)
+	}
+
 	return validateOutofBoundArrayParams(arrayIndexParamRefs, arrayParamsLengths)
 }
diff --git a/pkg/apis/pipeline/v1/task_validation_test.go b/pkg/apis/pipeline/v1/task_validation_test.go
index 5fa4d763f19..1ed46b6644e 100644
--- a/pkg/apis/pipeline/v1/task_validation_test.go
+++ b/pkg/apis/pipeline/v1/task_validation_test.go
@@ -1745,6 +1745,7 @@ func TestValidateParamArrayIndex(t *testing.T) {
 		name          string
 		params        []v1.Param
 		taskspec      *v1.TaskSpec
+		apiFields     string
 		expectedError error
 	}{{
 		name: "steps reference invalid",
@@ -1913,11 +1914,56 @@ func TestValidateParamArrayIndex(t *testing.T) {
 			},
 		},
 		expectedError: fmt.Errorf("non-existent param references:[%v]", "$(params.array-params[3])"),
+	}, {
+		name: "stable gate not allowed",
+		params: []v1.Param{{
+			Name:  "array-params",
+			Value: *v1.NewStructuredValues("bar", "foo"),
+		}},
+		taskspec: &v1.TaskSpec{
+			Params: []v1.ParamSpec{{
+				Name:    "array-params",
+				Default: v1.NewStructuredValues("bar", "foo"),
+			}},
+			Sidecars: []v1.Sidecar{{
+				Script: "$(params.array-params[3])",
+			},
+			},
+		},
+		apiFields:     config.StableAPIFields,
+		expectedError: fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, []string{"$(params.array-params[3])"}),
+	}, {
+		name: "alpha gate allowed",
+		params: []v1.Param{{
+			Name:  "array-params",
+			Value: *v1.NewStructuredValues("bar", "foo"),
+		}},
+		taskspec: &v1.TaskSpec{
+			Params: []v1.ParamSpec{{
+				Name:    "array-params",
+				Default: v1.NewStructuredValues("bar", "foo"),
+			}},
+			Sidecars: []v1.Sidecar{{
+				Script: "$(params.array-params[3])",
+			},
+			},
+		},
+		apiFields:     config.AlphaAPIFields,
+		expectedError: fmt.Errorf("non-existent param references:[%v]", "$(params.array-params[3])"),
 	},
 	}
 	for _, tc := range tcs {
 		t.Run(tc.name, func(t *testing.T) {
-			ctx := config.ToContext(context.Background(), &config.Config{FeatureFlags: &config.FeatureFlags{EnableAPIFields: "alpha"}})
+			// set default API fields to "beta" if not specified
+			ctx := context.Background()
+			switch tc.apiFields {
+			case config.AlphaAPIFields:
+				ctx = config.EnableAlphaAPIFields(ctx)
+			case config.StableAPIFields:
+				ctx = config.EnableStableAPIFields(ctx)
+			default:
+				ctx = config.EnableBetaAPIFields(ctx)
+			}
 			err := tc.taskspec.ValidateParamArrayIndex(ctx, tc.params)
 			if d := cmp.Diff(tc.expectedError.Error(), err.Error()); d != "" {
 				t.Errorf("validateParamArrayIndex() errors diff %s", diff.PrintWantGot(d))
diff --git a/pkg/apis/pipeline/v1beta1/pipeline_validation.go b/pkg/apis/pipeline/v1beta1/pipeline_validation.go
index c2456a51480..1143c7f550f 100644
--- a/pkg/apis/pipeline/v1beta1/pipeline_validation.go
+++ b/pkg/apis/pipeline/v1beta1/pipeline_validation.go
@@ -430,10 +430,6 @@ func validateResultsFromMatrixedPipelineTasksNotConsumed(tasks []PipelineTask, f
 // error is returned when the array indexing reference is out of bound of the array param
 // e.g. if a param reference of $(params.array-param[2]) and the array param is of length 2.
 func (ps *PipelineSpec) ValidateParamArrayIndex(ctx context.Context, params Params) error {
-	if !config.CheckAlphaOrBetaAPIFields(ctx) {
-		return nil
-	}
-
 	// Collect all array params lengths
 	arrayParamsLengths := ps.Params.extractParamArrayLengths()
 	for k, v := range params.extractParamArrayLengths() {
@@ -471,5 +467,10 @@ func (ps *PipelineSpec) ValidateParamArrayIndex(ctx context.Context, params Para
 		arrayIndexParamRefs = append(arrayIndexParamRefs, extractArrayIndexingParamRefs(p)...)
 	}
 
+	// if there are array indexing param references, the api feature gate needs to be set to `alpha` or `beta`
+	if len(arrayIndexParamRefs) > 0 && !config.CheckAlphaOrBetaAPIFields(ctx) {
+		return fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, arrayIndexParamRefs)
+	}
+
 	return validateOutofBoundArrayParams(arrayIndexParamRefs, arrayParamsLengths)
 }
diff --git a/pkg/apis/pipeline/v1beta1/pipeline_validation_test.go b/pkg/apis/pipeline/v1beta1/pipeline_validation_test.go
index bb4e2e5ab5c..c2d39958265 100644
--- a/pkg/apis/pipeline/v1beta1/pipeline_validation_test.go
+++ b/pkg/apis/pipeline/v1beta1/pipeline_validation_test.go
@@ -3358,14 +3358,11 @@ func enableFeatures(t *testing.T, features []string) func(context.Context) conte
 }
 
 func TestValidateParamArrayIndex_valid(t *testing.T) {
-	ctx := context.Background()
-	cfg := config.FromContextOrDefaults(ctx)
-	cfg.FeatureFlags.EnableAPIFields = config.BetaAPIFields
-	ctx = config.ToContext(ctx, cfg)
 	for _, tt := range []struct {
-		name     string
-		original PipelineSpec
-		params   []Param
+		name      string
+		original  PipelineSpec
+		params    []Param
+		apiFields string
 	}{{
 		name: "single parameter",
 		original: PipelineSpec{
@@ -3381,7 +3378,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "single parameter with when expression",
 		original: PipelineSpec{
@@ -3397,7 +3395,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				}},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "pipeline parameter nested inside task parameter",
 		original: PipelineSpec{
@@ -3412,7 +3411,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				},
 			}},
 		},
-		params: nil, // no parameter values.
+		params:    nil, // no parameter values.
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "array parameter",
 		original: PipelineSpec{
@@ -3430,6 +3430,7 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 		params: []Param{
 			{Name: "second-param", Value: *NewStructuredValues("second-value", "array")},
 		},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "parameter evaluation with final tasks",
 		original: PipelineSpec{
@@ -3449,7 +3450,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				}},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "parameter evaluation with both tasks and final tasks",
 		original: PipelineSpec{
@@ -3475,7 +3477,8 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				}},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "parameter references with bracket notation and special characters",
 		original: PipelineSpec{
@@ -3499,6 +3502,7 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 			{Name: "second/param", Value: *NewStructuredValues("second-value", "second-value-again")},
 			{Name: "fourth/param", Value: *NewStructuredValues("fourth-value", "fourth-value-again")},
 		},
+		apiFields: config.BetaAPIFields,
 	}, {
 		name: "single parameter in workspace subpath",
 		original: PipelineSpec{
@@ -3520,10 +3524,29 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 				},
 			}},
 		},
-		params: []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+	}, {
+		name: "validation with alpha gate",
+		original: PipelineSpec{
+			Params: []ParamSpec{
+				{Name: "first-param", Type: ParamTypeArray, Default: NewStructuredValues("default-value", "default-value-again")},
+				{Name: "second-param", Type: ParamTypeString},
+			},
+			Tasks: []PipelineTask{{
+				Params: []Param{
+					{Name: "first-task-first-param", Value: *NewStructuredValues("$(params.first-param[1])")},
+					{Name: "first-task-second-param", Value: *NewStructuredValues("$(params.second-param[0])")},
+					{Name: "first-task-third-param", Value: *NewStructuredValues("static value")},
+				},
+			}},
+		},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.AlphaAPIFields,
 	},
 	} {
 		tt := tt // capture range variable
+		ctx := config.SetEnableAPIFields(context.Background(), tt.apiFields)
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 			err := tt.original.ValidateParamArrayIndex(ctx, tt.params)
@@ -3535,15 +3558,12 @@ func TestValidateParamArrayIndex_valid(t *testing.T) {
 }
 
 func TestValidateParamArrayIndex_invalid(t *testing.T) {
-	ctx := context.Background()
-	cfg := config.FromContextOrDefaults(ctx)
-	cfg.FeatureFlags.EnableAPIFields = config.BetaAPIFields
-	ctx = config.ToContext(ctx, cfg)
 	for _, tt := range []struct {
-		name     string
-		original PipelineSpec
-		params   []Param
-		expected error
+		name      string
+		original  PipelineSpec
+		params    []Param
+		apiFields string
+		expected  error
 	}{{
 		name: "single parameter reference out of bound",
 		original: PipelineSpec{
@@ -3559,8 +3579,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "single parameter reference with when expression out of bound",
 		original: PipelineSpec{
@@ -3576,8 +3597,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				}},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "pipeline parameter reference nested inside task parameter out of bound",
 		original: PipelineSpec{
@@ -3592,8 +3614,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   nil, // no parameter values.
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    nil, // no parameter values.
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "array parameter reference out of bound",
 		original: PipelineSpec{
@@ -3611,7 +3634,8 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 		params: []Param{
 			{Name: "second-param", Value: *NewStructuredValues("second-value", "array")},
 		},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[3]) $(params.second-param[4])]"),
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[3]) $(params.second-param[4])]"),
 	}, {
 		name: "object parameter reference out of bound",
 		original: PipelineSpec{
@@ -3631,7 +3655,8 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 		params: []Param{
 			{Name: "second-param", Value: *NewStructuredValues("second-value", "array")},
 		},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[4]) $(params.second-param[4])]"),
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[4]) $(params.second-param[4])]"),
 	}, {
 		name: "parameter evaluation with final tasks reference out of bound",
 		original: PipelineSpec{
@@ -3651,8 +3676,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				}},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[2])]"),
 	}, {
 		name: "parameter evaluation with both tasks and final tasks reference out of bound",
 		original: PipelineSpec{
@@ -3683,8 +3709,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 					}},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.first-param[3]) $(params.first-param[4]) $(params.second-param[2]) $(params.second-param[3]) $(params.second-param[4])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.first-param[3]) $(params.first-param[4]) $(params.second-param[2]) $(params.second-param[3]) $(params.second-param[4])]"),
 	}, {
 		name: "parameter in matrix reference out of bound",
 		original: PipelineSpec{
@@ -3701,8 +3728,9 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2])]"),
 	}, {
 		name: "parameter references with bracket notation and special characters reference out of bound",
 		original: PipelineSpec{
@@ -3726,7 +3754,8 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 			{Name: "second/param", Value: *NewStructuredValues("second-value", "second-value-again")},
 			{Name: "fourth/param", Value: *NewStructuredValues("fourth-value", "fourth-value-again")},
 		},
-		expected: fmt.Errorf("non-existent param references:[$(params[\"first.param\"][2]) $(params[\"second/param\"][2]) $(params['fourth/param'][2]) $(params['third.param'][2])]"),
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params[\"first.param\"][2]) $(params[\"second/param\"][2]) $(params['fourth/param'][2]) $(params['third.param'][2])]"),
 	}, {
 		name: "single parameter in workspace subpath reference out of bound",
 		original: PipelineSpec{
@@ -3748,13 +3777,57 @@ func TestValidateParamArrayIndex_invalid(t *testing.T) {
 				},
 			}},
 		},
-		params:   []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
-		expected: fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[3])]"),
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.BetaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[3])]"),
+	}, {
+		name: "validation alpha feature gate",
+		original: PipelineSpec{
+			Params: []ParamSpec{
+				{Name: "first-param", Type: ParamTypeArray, Default: NewStructuredValues("default-value", "default-value-again")},
+				{Name: "second-param", Type: ParamTypeArray},
+			},
+			Tasks: []PipelineTask{{
+				Params: []Param{
+					{Name: "first-task-first-param", Value: *NewStructuredValues("$(params.first-param[2])")},
+					{Name: "first-task-second-param", Value: *NewStructuredValues("static value")},
+				},
+				Workspaces: []WorkspacePipelineTaskBinding{
+					{
+						Name:      "first-workspace",
+						Workspace: "first-workspace",
+						SubPath:   "$(params.second-param[3])",
+					},
+				},
+			}},
+		},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.AlphaAPIFields,
+		expected:  fmt.Errorf("non-existent param references:[$(params.first-param[2]) $(params.second-param[3])]"),
+	}, {
+		name: "stable gate not allowed",
+		original: PipelineSpec{
+			Params: []ParamSpec{
+				{Name: "first-param", Type: ParamTypeArray, Default: NewStructuredValues("default-value", "default-value-again")},
+				{Name: "second-param", Type: ParamTypeString},
+			},
+			Tasks: []PipelineTask{{
+				Params: []Param{
+					{Name: "first-task-first-param", Value: *NewStructuredValues("$(params.first-param[2])")},
+					{Name: "first-task-second-param", Value: *NewStructuredValues("$(params.second-param[2])")},
+					{Name: "first-task-third-param", Value: *NewStructuredValues("static value")},
+				},
+			}},
+		},
+		params:    []Param{{Name: "second-param", Value: *NewStructuredValues("second-value", "second-value-again")}},
+		apiFields: config.StableAPIFields,
+		expected:  fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, []string{"$(params.first-param[2])", "$(params.second-param[2])"}),
 	},
 	} {
 		tt := tt // capture range variable
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
+			ctx := config.SetEnableAPIFields(context.Background(), tt.apiFields)
 			err := tt.original.ValidateParamArrayIndex(ctx, tt.params)
 			if d := cmp.Diff(tt.expected.Error(), err.Error()); d != "" {
 				t.Errorf("ValidateParamArrayIndex() errors diff %s", diff.PrintWantGot(d))
diff --git a/pkg/apis/pipeline/v1beta1/task_validation.go b/pkg/apis/pipeline/v1beta1/task_validation.go
index 1486c38aaa6..ee28b926ff0 100644
--- a/pkg/apis/pipeline/v1beta1/task_validation.go
+++ b/pkg/apis/pipeline/v1beta1/task_validation.go
@@ -607,11 +607,6 @@ func isParamRefs(s string) bool {
 // - `trParams` are params from taskrun.
 // - `taskSpec` contains params declarations.
 func (ts *TaskSpec) ValidateParamArrayIndex(ctx context.Context, params Params) error {
-	cfg := config.FromContextOrDefaults(ctx)
-	if cfg.FeatureFlags.EnableAPIFields != config.AlphaAPIFields {
-		return nil
-	}
-
 	// Collect all array params lengths
 	arrayParamsLengths := ts.Params.extractParamArrayLengths()
 	for k, v := range params.extractParamArrayLengths() {
@@ -634,5 +629,10 @@ func (ts *TaskSpec) ValidateParamArrayIndex(ctx context.Context, params Params)
 		arrayIndexParamRefs = append(arrayIndexParamRefs, extractArrayIndexingParamRefs(p)...)
 	}
 
+	// if there are array indexing param references, the api feature gate needs to be set to `alpha` or `beta`
+	if len(arrayIndexParamRefs) > 0 && !config.CheckAlphaOrBetaAPIFields(ctx) {
+		return fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, arrayIndexParamRefs)
+	}
+
 	return validateOutofBoundArrayParams(arrayIndexParamRefs, arrayParamsLengths)
 }
diff --git a/pkg/apis/pipeline/v1beta1/task_validation_test.go b/pkg/apis/pipeline/v1beta1/task_validation_test.go
index 982655e2540..153b3b34615 100644
--- a/pkg/apis/pipeline/v1beta1/task_validation_test.go
+++ b/pkg/apis/pipeline/v1beta1/task_validation_test.go
@@ -1748,6 +1748,7 @@ func TestValidateParamArrayIndex(t *testing.T) {
 		name          string
 		params        []v1beta1.Param
 		taskspec      *v1beta1.TaskSpec
+		apiFields     string
 		expectedError error
 	}{{
 		name: "steps reference invalid",
@@ -1916,11 +1917,56 @@ func TestValidateParamArrayIndex(t *testing.T) {
 			},
 		},
 		expectedError: fmt.Errorf("non-existent param references:[%v]", "$(params.array-params[3])"),
+	}, {
+		name: "stable gate not allowed",
+		params: []v1beta1.Param{{
+			Name:  "array-params",
+			Value: *v1beta1.NewStructuredValues("bar", "foo"),
+		}},
+		taskspec: &v1beta1.TaskSpec{
+			Params: []v1beta1.ParamSpec{{
+				Name:    "array-params",
+				Default: v1beta1.NewStructuredValues("bar", "foo"),
+			}},
+			Sidecars: []v1beta1.Sidecar{{
+				Script: "$(params.array-params[3])",
+			},
+			},
+		},
+		apiFields:     config.StableAPIFields,
+		expectedError: fmt.Errorf(`invalid parameter expression %s: indexing into array params requires "enable-api-fields" feature gate to be "alpha" or "beta"`, []string{"$(params.array-params[3])"}),
+	}, {
+		name: "alpha gate allowed",
+		params: []v1beta1.Param{{
+			Name:  "array-params",
+			Value: *v1beta1.NewStructuredValues("bar", "foo"),
+		}},
+		taskspec: &v1beta1.TaskSpec{
+			Params: []v1beta1.ParamSpec{{
+				Name:    "array-params",
+				Default: v1beta1.NewStructuredValues("bar", "foo"),
+			}},
+			Sidecars: []v1beta1.Sidecar{{
+				Script: "$(params.array-params[3])",
+			},
+			},
+		},
+		apiFields:     config.AlphaAPIFields,
+		expectedError: fmt.Errorf("non-existent param references:[%v]", "$(params.array-params[3])"),
 	},
 	}
 	for _, tc := range tcs {
 		t.Run(tc.name, func(t *testing.T) {
-			ctx := config.ToContext(context.Background(), &config.Config{FeatureFlags: &config.FeatureFlags{EnableAPIFields: "alpha"}})
+			// set default API fields to "beta" if not specified
+			ctx := context.Background()
+			switch tc.apiFields {
+			case config.AlphaAPIFields:
+				ctx = config.EnableAlphaAPIFields(ctx)
+			case config.StableAPIFields:
+				ctx = config.EnableStableAPIFields(ctx)
+			default:
+				ctx = config.EnableBetaAPIFields(ctx)
+			}
 			err := tc.taskspec.ValidateParamArrayIndex(ctx, tc.params)
 			if d := cmp.Diff(tc.expectedError.Error(), err.Error()); d != "" {
 				t.Errorf("validateParamArrayIndex() errors diff %s", diff.PrintWantGot(d))