diff --git a/packages/autop/CHANGELOG.md b/packages/autop/CHANGELOG.md
index 0f40e07f861653..918e47c7352990 100644
--- a/packages/autop/CHANGELOG.md
+++ b/packages/autop/CHANGELOG.md
@@ -1,3 +1,9 @@
+## Master
+
+### New feature
+
+- Include TypeScript type declarations ([#20669](https://github.com/WordPress/gutenberg/pull/20669))
+
 ## 2.3.0 (2019-05-21)
 
 ### Bug Fix
diff --git a/packages/autop/package.json b/packages/autop/package.json
index 9a4f5d7fbaaacb..185eaf491c9a06 100644
--- a/packages/autop/package.json
+++ b/packages/autop/package.json
@@ -20,6 +20,7 @@
 	"main": "build/index.js",
 	"module": "build-module/index.js",
 	"react-native": "src/index",
+	"types": "build-types",
 	"sideEffects": false,
 	"dependencies": {
 		"@babel/runtime": "^7.8.3"
diff --git a/packages/autop/src/index.js b/packages/autop/src/index.js
index 3a0fc7fa73600e..b2c605620852f3 100644
--- a/packages/autop/src/index.js
+++ b/packages/autop/src/index.js
@@ -1,7 +1,7 @@
 /**
  * The regular expression for an HTML element.
  *
- * @type {string}
+ * @type {RegExp}
  */
 const htmlSplitRegex = ( () => {
 	/* eslint-disable no-multi-spaces */
@@ -52,7 +52,7 @@ const htmlSplitRegex = ( () => {
  * Separate HTML elements and comments from the text.
  *
  * @param  {string} input The text which has to be formatted.
- * @return {Array}        The formatted text.
+ * @return {string[]}        The formatted text.
  */
 function htmlSplit( input ) {
 	const parts = [];
@@ -60,9 +60,15 @@ function htmlSplit( input ) {
 
 	let match;
 	while ( ( match = workingInput.match( htmlSplitRegex ) ) ) {
-		parts.push( workingInput.slice( 0, match.index ) );
+		// The `match` result, when invoked on a RegExp with the `g` flag (`/foo/g`) will not include `index`.
+		// If the `g` flag is omitted, `index` is included.
+		// `htmlSplitRegex` does not have the `g` flag so we can assert it will have an index number.
+		// Assert `match.index` is a number.
+		const index = /** @type {number} */ ( match.index );
+
+		parts.push( workingInput.slice( 0, index ) );
 		parts.push( match[ 0 ] );
-		workingInput = workingInput.slice( match.index + match[ 0 ].length );
+		workingInput = workingInput.slice( index + match[ 0 ].length );
 	}
 
 	if ( workingInput.length ) {
@@ -75,9 +81,9 @@ function htmlSplit( input ) {
 /**
  * Replace characters or phrases within HTML elements only.
  *
- * @param  {string} haystack     The text which has to be formatted.
- * @param  {Object} replacePairs In the form {from: 'to', ...}.
- * @return {string}              The formatted text.
+ * @param  {string}                haystack     The text which has to be formatted.
+ * @param  {Record<string,string>} replacePairs In the form {from: 'to', …}.
+ * @return {string}                             The formatted text.
  */
 function replaceInHtmlTags( haystack, replacePairs ) {
 	// Find all elements.
@@ -337,6 +343,7 @@ export function removep( html ) {
 		'blockquote|ul|ol|li|dl|dt|dd|table|thead|tbody|tfoot|tr|th|td|h[1-6]|fieldset|figure';
 	const blocklist1 = blocklist + '|div|p';
 	const blocklist2 = blocklist + '|pre';
+	/** @type {string[]} */
 	const preserve = [];
 	let preserveLinebreaks = false;
 	let preserveBr = false;
@@ -399,7 +406,7 @@ export function removep( html ) {
 	html = html.replace( /\n[\s\u00a0]+\n/g, '\n\n' );
 
 	// Replace <br> tags with line breaks.
-	html = html.replace( /(\s*)<br ?\/?>\s*/gi, function( match, space ) {
+	html = html.replace( /(\s*)<br ?\/?>\s*/gi, function( _, space ) {
 		if ( space && space.indexOf( '\n' ) !== -1 ) {
 			return '\n\n';
 		}
@@ -470,7 +477,7 @@ export function removep( html ) {
 	// Restore preserved tags.
 	if ( preserve.length ) {
 		html = html.replace( /<wp-preserve>/g, function() {
-			return preserve.shift();
+			return /** @type {string} */ ( preserve.shift() );
 		} );
 	}
 
diff --git a/packages/autop/tsconfig.json b/packages/autop/tsconfig.json
new file mode 100644
index 00000000000000..1a0a90bc8cb582
--- /dev/null
+++ b/packages/autop/tsconfig.json
@@ -0,0 +1,9 @@
+{
+	"extends": "../../tsconfig.base.json",
+	"compilerOptions": {
+		"rootDir": "src",
+		"declarationDir": "build-types"
+	},
+	"references": [ { "path": "../dom-ready" } ],
+	"include": [ "src/**/*" ]
+}
diff --git a/packages/escape-html/CHANGELOG.md b/packages/escape-html/CHANGELOG.md
index 9f38d3c2bb14ef..ab18f8a217b329 100644
--- a/packages/escape-html/CHANGELOG.md
+++ b/packages/escape-html/CHANGELOG.md
@@ -1,3 +1,9 @@
+## Master
+
+### New feature
+
+- Include TypeScript type declarations ([#20669](https://github.com/WordPress/gutenberg/pull/20669))
+
 ## 1.2.0 (2019-03-20)
 
 - Add fix for WordPress wptexturize greater-than tokenize bug (see https://core.trac.wordpress.org/ticket/45387)
diff --git a/packages/escape-html/package.json b/packages/escape-html/package.json
index fab30cccc0bece..7f208d33df38a0 100644
--- a/packages/escape-html/package.json
+++ b/packages/escape-html/package.json
@@ -19,6 +19,7 @@
 	"main": "build/index.js",
 	"module": "build-module/index.js",
 	"react-native": "src/index",
+	"types": "build-types",
 	"sideEffects": false,
 	"dependencies": {
 		"@babel/runtime": "^7.8.3"
diff --git a/packages/escape-html/tsconfig.json b/packages/escape-html/tsconfig.json
new file mode 100644
index 00000000000000..3c2c31f506f132
--- /dev/null
+++ b/packages/escape-html/tsconfig.json
@@ -0,0 +1,8 @@
+{
+	"extends": "../../tsconfig.base.json",
+	"compilerOptions": {
+		"rootDir": "src",
+		"declarationDir": "build-types"
+	},
+	"include": [ "src/**/*" ]
+}
diff --git a/packages/html-entities/CHANGELOG.md b/packages/html-entities/CHANGELOG.md
index f9355f9f968653..5d0ba8e3277ef0 100644
--- a/packages/html-entities/CHANGELOG.md
+++ b/packages/html-entities/CHANGELOG.md
@@ -1,3 +1,9 @@
+## Master
+
+### New feature
+
+- Include TypeScript type declarations ([#20669](https://github.com/WordPress/gutenberg/pull/20669))
+
 ## 2.0.2 (2018-12-12)
 
 ## 2.0.1 (2018-11-21)
diff --git a/packages/html-entities/package.json b/packages/html-entities/package.json
index 5e0cb8c0f1d047..f3df5c2856ffaa 100644
--- a/packages/html-entities/package.json
+++ b/packages/html-entities/package.json
@@ -21,6 +21,7 @@
 	"main": "build/index.js",
 	"module": "build-module/index.js",
 	"react-native": "src/index",
+	"types": "build-types",
 	"dependencies": {
 		"@babel/runtime": "^7.8.3"
 	},
diff --git a/packages/html-entities/src/index.js b/packages/html-entities/src/index.js
index 615087f992e78d..25e440748765cf 100644
--- a/packages/html-entities/src/index.js
+++ b/packages/html-entities/src/index.js
@@ -1,3 +1,4 @@
+/** @type {HTMLTextAreaElement} */
 let _decodeTextArea;
 
 /**
@@ -36,5 +37,23 @@ export function decodeEntities( html ) {
 	_decodeTextArea.innerHTML = html;
 	const decoded = _decodeTextArea.textContent;
 	_decodeTextArea.innerHTML = '';
-	return decoded;
+
+	/**
+	 * Cast to string, HTMLTextAreaElement should always have `string` textContent.
+	 *
+	 * > The `textContent` property of the `Node` interface represents the text content of the
+	 * > node and its descendants.
+	 * >
+	 * > Value: A string or `null`
+	 * >
+	 * > * If the node is a `document` or a Doctype, `textContent` returns `null`.
+	 * > * If the node is a CDATA section, comment, processing instruction, or text node,
+	 * >   textContent returns the text inside the node, i.e., the `Node.nodeValue`.
+	 * > * For other node types, `textContent returns the concatenation of the textContent of
+	 * >   every child node, excluding comments and processing instructions. (This is an empty
+	 * >   string if the node has no children.)
+	 *
+	 * @see https://developer.mozilla.org/en-US/docs/Web/API/Node/textContent
+	 */
+	return /** @type {string} */ ( decoded );
 }
diff --git a/packages/html-entities/tsconfig.json b/packages/html-entities/tsconfig.json
new file mode 100644
index 00000000000000..3c2c31f506f132
--- /dev/null
+++ b/packages/html-entities/tsconfig.json
@@ -0,0 +1,8 @@
+{
+	"extends": "../../tsconfig.base.json",
+	"compilerOptions": {
+		"rootDir": "src",
+		"declarationDir": "build-types"
+	},
+	"include": [ "src/**/*" ]
+}
diff --git a/tsconfig.json b/tsconfig.json
index d5c74947987457..c44723b21e2f58 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,8 +2,11 @@
 	"references": [
 		{ "path": "bin" },
 		{ "path": "packages/a11y" },
+		{ "path": "packages/autop" },
 		{ "path": "packages/blob" },
 		{ "path": "packages/dom-ready" },
+		{ "path": "packages/escape-html" },
+		{ "path": "packages/html-entities" },
 		{ "path": "packages/i18n" },
 		{ "path": "packages/is-shallow-equal" },
 		{ "path": "packages/priority-queue" },