diff --git a/src/Executor/Values.php b/src/Executor/Values.php
index 06c9532fd..9a14d116a 100644
--- a/src/Executor/Values.php
+++ b/src/Executor/Values.php
@@ -12,6 +12,7 @@
 use GraphQL\Language\AST\FragmentSpreadNode;
 use GraphQL\Language\AST\InlineFragmentNode;
 use GraphQL\Language\AST\NodeList;
+use GraphQL\Language\AST\NullValueNode;
 use GraphQL\Language\AST\VariableNode;
 use GraphQL\Language\AST\VariableDefinitionNode;
 use GraphQL\Language\Printer;
@@ -131,10 +132,16 @@ public static function getArgumentValues($def, $node, $variableValues = null)
                         [$node]
                     );
                 }
+            } else if ($argumentNode->value instanceof NullValueNode) {
+                // Explicitly set null values should produce the defaultValue if available
+                if ($argDef->defaultValueExists()) {
+                    $coercedValues[$name] = $argDef->defaultValue;
+                }
             } else if ($argumentNode->value instanceof VariableNode) {
                 $variableName = $argumentNode->value->name->value;
 
-                if ($variableValues && array_key_exists($variableName, $variableValues)) {
+                // Explicitly set null values should produce the defaultValue if available
+                if ($variableValues && array_key_exists($variableName, $variableValues) && $variableValues[$variableName] !== null) {
                     // Note: this does not check that this variable value is correct.
                     // This assumes that this query has been validated and the variable
                     // usage here is of the correct type.
@@ -152,6 +159,12 @@ public static function getArgumentValues($def, $node, $variableValues = null)
             } else {
                 $valueNode = $argumentNode->value;
                 $coercedValue = AST::valueFromAST($valueNode, $argType, $variableValues);
+
+                // Explicitly set null values should produce the defaultValue if available
+                if ($coercedValue === null && $argDef->defaultValueExists()) {
+                    $coercedValue = $argDef->defaultValue;
+                }
+
                 if ($coercedValue === $undefined) {
                     $errors = DocumentValidator::isValidLiteralValue($argType, $valueNode);
                     $message = !empty($errors) ? ("\n" . implode("\n", $errors)) : '';
diff --git a/tests/Executor/VariablesTest.php b/tests/Executor/VariablesTest.php
index 418ed12d4..945f566cb 100644
--- a/tests/Executor/VariablesTest.php
+++ b/tests/Executor/VariablesTest.php
@@ -852,6 +852,36 @@ public function testWhenOmittedVariableProvided()
         );
     }
 
+    /**
+     * @it when null value variable provided
+     */
+    public function testWhenNullValueVariableProvided()
+    {
+        $ast = Parser::parse('query optionalVariable($optional: String) {
+            fieldWithDefaultArgumentValue(input: $optional)
+        }');
+
+        $this->assertEquals(
+            ['data' => ['fieldWithDefaultArgumentValue' => '"Hello World"']],
+            Executor::execute($this->schema(), $ast, null, null, ['optional' => null])->toArray()
+        );
+    }
+
+    /**
+     * @it when null value provided directly
+     */
+    public function testWhenNullValueProvidedDirectly()
+    {
+        $ast = Parser::parse('query {
+            fieldWithDefaultArgumentValue(input: null)
+        }');
+
+        $this->assertEquals(
+            ['data' => ['fieldWithDefaultArgumentValue' => '"Hello World"']],
+            Executor::execute($this->schema(), $ast)->toArray()
+        );
+    }
+
     /**
      * @it not when argument cannot be coerced
      */