diff --git a/.gitignore b/.gitignore
index 575b07fcd7f..03e9b7e136a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,6 +42,7 @@ packages/ckeditor5-engine/src/**/*.js
 packages/ckeditor5-enter/src/**/*.js
 packages/ckeditor5-essentials/src/**/*.js
 packages/ckeditor5-heading/src/**/*.js
+packages/ckeditor5-highlight/src/**/*.js
 packages/ckeditor5-horizontal-line/src/**/*.js
 packages/ckeditor5-language/src/**/*.js
 packages/ckeditor5-list/src/**/*.js
diff --git a/packages/ckeditor5-engine/src/index.ts b/packages/ckeditor5-engine/src/index.ts
index 2b48279d17d..da87dba9efa 100644
--- a/packages/ckeditor5-engine/src/index.ts
+++ b/packages/ckeditor5-engine/src/index.ts
@@ -64,7 +64,7 @@ export { default as Range } from './model/range';
 export { default as LiveRange } from './model/liverange';
 export { default as LivePosition } from './model/liveposition';
 export { default as Model } from './model/model';
-export { default as TreeWalker } from './model/treewalker';
+export { default as TreeWalker, type TreeWalkerValue } from './model/treewalker';
 export { default as Element } from './model/element';
 export { default as Position } from './model/position';
 export { default as DocumentFragment } from './model/documentfragment';
diff --git a/packages/ckeditor5-highlight/src/highlight.js b/packages/ckeditor5-highlight/_src/highlight.js
similarity index 100%
rename from packages/ckeditor5-highlight/src/highlight.js
rename to packages/ckeditor5-highlight/_src/highlight.js
diff --git a/packages/ckeditor5-highlight/src/highlightcommand.js b/packages/ckeditor5-highlight/_src/highlightcommand.js
similarity index 100%
rename from packages/ckeditor5-highlight/src/highlightcommand.js
rename to packages/ckeditor5-highlight/_src/highlightcommand.js
diff --git a/packages/ckeditor5-highlight/src/highlightediting.js b/packages/ckeditor5-highlight/_src/highlightediting.js
similarity index 100%
rename from packages/ckeditor5-highlight/src/highlightediting.js
rename to packages/ckeditor5-highlight/_src/highlightediting.js
diff --git a/packages/ckeditor5-highlight/src/highlightui.js b/packages/ckeditor5-highlight/_src/highlightui.js
similarity index 100%
rename from packages/ckeditor5-highlight/src/highlightui.js
rename to packages/ckeditor5-highlight/_src/highlightui.js
diff --git a/packages/ckeditor5-highlight/src/index.js b/packages/ckeditor5-highlight/_src/index.js
similarity index 100%
rename from packages/ckeditor5-highlight/src/index.js
rename to packages/ckeditor5-highlight/_src/index.js
diff --git a/packages/ckeditor5-highlight/package.json b/packages/ckeditor5-highlight/package.json
index 356ef883f04..44fc3ff43b5 100644
--- a/packages/ckeditor5-highlight/package.json
+++ b/packages/ckeditor5-highlight/package.json
@@ -10,7 +10,7 @@
     "ckeditor5-plugin",
     "ckeditor5-dll"
   ],
-  "main": "src/index.js",
+  "main": "src/index.ts",
   "dependencies": {
     "ckeditor5": "^35.4.0"
   },
@@ -28,6 +28,7 @@
     "@ckeditor/ckeditor5-theme-lark": "^35.4.0",
     "@ckeditor/ckeditor5-typing": "^35.4.0",
     "@ckeditor/ckeditor5-utils": "^35.4.0",
+    "typescript": "^4.8.4",
     "webpack": "^5.58.1",
     "webpack-cli": "^4.9.0"
   },
@@ -47,12 +48,16 @@
   "files": [
     "lang",
     "src",
+    "src/**/*.js",
+    "src/**/*.d.ts",
     "theme",
     "build",
     "ckeditor5-metadata.json",
     "CHANGELOG.md"
   ],
   "scripts": {
-    "dll:build": "webpack"
+    "dll:build": "webpack",
+    "build": "tsc -p ./tsconfig.release.json",
+    "postversion": "npm run build"
   }
 }
diff --git a/packages/ckeditor5-highlight/src/highlight.ts b/packages/ckeditor5-highlight/src/highlight.ts
new file mode 100644
index 00000000000..5ccd7b66c38
--- /dev/null
+++ b/packages/ckeditor5-highlight/src/highlight.ts
@@ -0,0 +1,225 @@
+/**
+ * @license Copyright (c) 2003-2023, CKSource Holding sp. z o.o. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/**
+ * @module highlight/highlight
+ */
+
+import { Plugin, type PluginDependencies } from 'ckeditor5/src/core';
+
+import HighlightEditing from './highlightediting';
+import HighlightUI from './highlightui';
+
+/**
+ * The highlight plugin.
+ *
+ * For a detailed overview, check the {@glink features/highlight Highlight feature} documentation.
+ *
+ * This is a "glue" plugin which loads the {@link module:highlight/highlightediting~HighlightEditing} and
+ * {@link module:highlight/highlightui~HighlightUI} plugins.
+ */
+export default class Highlight extends Plugin {
+	/**
+	 * @inheritDoc
+	 */
+	public static get requires(): PluginDependencies {
+		return [ HighlightEditing, HighlightUI ];
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public static get pluginName(): 'Highlight' {
+		return 'Highlight';
+	}
+}
+
+/**
+ * The highlight option descriptor. See {@link module:highlight/highlight~HighlightConfig} to learn more.
+ *
+ * ```ts
+ * {
+ * 	model: 'pinkMarker',
+ * 	class: 'marker-pink',
+ * 	title: 'Pink Marker',
+ * 	color: 'var(--ck-highlight-marker-pink)',
+ * 	type: 'marker'
+ * }
+ * ```
+ */
+export interface HighlightOption {
+
+	/**
+	 * The user-readable title of the option.
+	 */
+	title: string;
+
+	/**
+	 * The unique attribute value in the model.
+	 */
+	model: string;
+
+	/**
+	 * The CSS `var()` used for the highlighter. The color is used in the user interface to represent the highlighter.
+	 * There is a possibility to use the default color format like rgb, hex or hsl, but you need to care about the color of `<mark>`
+	 * by adding CSS classes definition.
+	 */
+	color: string;
+
+	/**
+	 * The CSS class used on the `<mark>` element in the view. It should match the `color` setting.
+	 */
+	class: string;
+
+	/**
+	 * The type of highlighter:
+	 *
+	 * * `'marker'` &ndash; Uses the `color` as the `background-color` style,
+	 * * `'pen'` &ndash; Uses the `color` as the font `color` style.
+	 */
+	type: 'marker' | 'pen';
+}
+
+/**
+ * The configuration of the {@link module:highlight/highlight~Highlight highlight feature}.
+ * ```ts
+ * ClassicEditor
+ * 	.create( editorElement, {
+ * 		highlight:  ... // Highlight feature configuration.
+ * 	} )
+ * 	.then( ... )
+ * 	.catch( ... );
+ * ```
+ * See {@link module:core/editor/editorconfig~EditorConfig all editor options}.
+ */
+export interface HighlightConfig {
+
+	/**
+	 * The available highlight options. The default value is:
+	 * ```ts
+	 * options: [
+	 * 	{
+	 * 		model: 'yellowMarker',
+	 * 		class: 'marker-yellow',
+	 * 		title: 'Yellow marker',
+	 * 		color: 'var(--ck-highlight-marker-yellow)',
+	 * 		type: 'marker'
+	 * 	},
+	 * 	{
+	 * 		model: 'greenMarker',
+	 * 		class: 'marker-green',
+	 * 		title: 'Green marker',
+	 * 		color: 'var(--ck-highlight-marker-green)',
+	 * 		type: 'marker'
+	 * 	},
+	 * 	{
+	 * 		model: 'pinkMarker',
+	 * 		class: 'marker-pink',
+	 * 		title: 'Pink marker',
+	 * 		color: 'var(--ck-highlight-marker-pink)',
+	 * 		type: 'marker'
+	 * 	},
+	 * 	{
+	 * 		model: 'blueMarker',
+	 * 		class: 'marker-blue',
+	 * 		title: 'Blue marker',
+	 * 		color: 'var(--ck-highlight-marker-blue)',
+	 * 		type: 'marker'
+	 * 	},
+	 * 	{
+	 * 		model: 'redPen',
+	 * 		class: 'pen-red',
+	 * 		title: 'Red pen',
+	 * 		color: 'var(--ck-highlight-pen-red)',
+	 * 		type: 'pen'
+	 * 	},
+	 * 	{
+	 * 		model: 'greenPen',
+	 * 		class: 'pen-green',
+	 * 		title: 'Green pen',
+	 * 		color: 'var(--ck-highlight-pen-green)',
+	 * 		type: 'pen'
+	 * 	}
+	 * ]
+	 * ```
+	 *
+	 * There are two types of highlighters available:
+	 *
+	 * * `'marker'` &ndash; Rendered as a `<mark>` element, styled with the `background-color`.
+	 * * `'pen'` &ndash; Rendered as a `<mark>` element, styled with the font `color`.
+	 *
+	 * **Note**: The highlight feature provides a stylesheet with the CSS classes and corresponding colors defined
+	 * as CSS variables.
+	 *
+	 * ```ts
+	 * :root {
+	 * 	--ck-highlight-marker-yellow: #fdfd77;
+	 * 	--ck-highlight-marker-green: #63f963;
+	 * 	--ck-highlight-marker-pink: #fc7999;
+	 * 	--ck-highlight-marker-blue: #72cdfd;
+	 * 	--ck-highlight-pen-red: #e91313;
+	 * 	--ck-highlight-pen-green: #118800;
+	 * }
+	 *
+	 * .marker-yellow { ... }
+	 * .marker-green { ... }
+	 * .marker-pink { ... }
+	 * .marker-blue { ... }
+	 * .pen-red { ... }
+	 * .pen-green { ... }
+	 * ```
+	 *
+	 * It is possible to define the `color` property directly as `rgba(R, G, B, A)`,
+	 * `#RRGGBB[AA]` or `hsla(H, S, L, A)`. In such situation, the color will **only** apply to the UI of
+	 * the editor and the `<mark>` elements in the content must be styled by custom classes provided by
+	 * a dedicated stylesheet.
+	 *
+	 * **Note**: It is recommended for the `color` property to correspond to the class in the content
+	 * stylesheet because it represents the highlighter in the user interface of the editor.
+	 *
+	 * ```ts
+	 * ClassicEditor
+	 * 	.create( editorElement, {
+	 * 		highlight: {
+	 * 			options: [
+	 * 				{
+	 * 					model: 'pinkMarker',
+	 * 					class: 'marker-pink',
+	 * 					title: 'Pink Marker',
+	 * 					color: 'var(--ck-highlight-marker-pink)',
+	 * 					type: 'marker'
+	 * 				},
+	 * 				{
+	 * 					model: 'redPen',
+	 * 					class: 'pen-red',
+	 * 					title: 'Red Pen',
+	 * 					color: 'var(--ck-highlight-pen-red)',
+	 * 					type: 'pen'
+	 * 				},
+	 * 			]
+	 * 		}
+	 * } )
+	 * .then( ... )
+	 * .catch( ... );
+	 * ```
+	 */
+	options: Array<HighlightOption>;
+}
+
+declare module '@ckeditor/ckeditor5-core' {
+	interface PluginsMap {
+		[ Highlight.pluginName ]: Highlight;
+	}
+
+	interface EditorConfig {
+
+		/**
+		 * The configuration of the {@link module:highlight/highlight~Highlight} feature.
+		 *
+		 * Read more in {@link module:highlight/highlight~HighlightConfig}.
+		 */
+		highlight?: HighlightConfig;
+	}
+}
diff --git a/packages/ckeditor5-highlight/src/highlightcommand.ts b/packages/ckeditor5-highlight/src/highlightcommand.ts
new file mode 100644
index 00000000000..5a6cd4e42b4
--- /dev/null
+++ b/packages/ckeditor5-highlight/src/highlightcommand.ts
@@ -0,0 +1,113 @@
+/**
+ * @license Copyright (c) 2003-2023, CKSource Holding sp. z o.o. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/**
+ * @module highlight/highlightcommand
+ */
+
+import { Command } from 'ckeditor5/src/core';
+import type { TreeWalkerValue } from 'ckeditor5/src/engine';
+
+/**
+ * The highlight command. It is used by the {@link module:highlight/highlightediting~HighlightEditing highlight feature}
+ * to apply the text highlighting.
+ *
+ * ```ts
+ * editor.execute( 'highlight', { value: 'greenMarker' } );
+ * ```
+ *
+ * **Note**: Executing the command without a value removes the attribute from the model. If the selection is collapsed
+ * inside a text with the highlight attribute, the command will remove the attribute from the entire range
+ * of that text.
+ */
+export default class HighlightCommand extends Command {
+	/**
+	 * A value indicating whether the command is active. If the selection has some highlight attribute,
+	 * it corresponds to the value of that attribute.
+	 *
+	 * @observable
+	 * @readonly
+	 */
+	declare public value: string | undefined;
+
+	/**
+	 * @inheritDoc
+	 */
+	public override refresh(): void {
+		const model = this.editor.model;
+		const doc = model.document;
+
+		this.value = doc.selection.getAttribute( 'highlight' ) as string | undefined;
+		this.isEnabled = model.schema.checkAttributeInSelection( doc.selection, 'highlight' );
+	}
+
+	/**
+	 * Executes the command.
+	 *
+	 * @param options Options for the executed command.
+	 * @param options.value The value to apply.
+	 *
+	 * @fires execute
+	 */
+	public override execute( options: { value?: string | null } = {} ): void {
+		const model = this.editor.model;
+		const document = model.document;
+		const selection = document.selection;
+
+		const highlighter = options.value;
+
+		model.change( writer => {
+			if ( selection.isCollapsed ) {
+				const position = selection.getFirstPosition()!;
+
+				// When selection is inside text with `highlight` attribute.
+				if ( selection.hasAttribute( 'highlight' ) ) {
+					// Find the full highlighted range.
+					const isSameHighlight = ( value: TreeWalkerValue ) => {
+						return value.item.hasAttribute( 'highlight' ) && value.item.getAttribute( 'highlight' ) === this.value;
+					};
+
+					const highlightStart = position.getLastMatchingPosition( isSameHighlight, { direction: 'backward' } );
+					const highlightEnd = position.getLastMatchingPosition( isSameHighlight );
+
+					const highlightRange = writer.createRange( highlightStart, highlightEnd );
+
+					// Then depending on current value...
+					if ( !highlighter || this.value === highlighter ) {
+						// ...remove attribute when passing highlighter different then current or executing "eraser".
+
+						// If we're at the end of the highlighted range, we don't want to remove highlight of the range.
+						if ( !position.isEqual( highlightEnd ) ) {
+							writer.removeAttribute( 'highlight', highlightRange );
+						}
+
+						writer.removeSelectionAttribute( 'highlight' );
+					} else {
+						// ...update `highlight` value.
+
+						// If we're at the end of the highlighted range, we don't want to change the highlight of the range.
+						if ( !position.isEqual( highlightEnd ) ) {
+							writer.setAttribute( 'highlight', highlighter, highlightRange );
+						}
+
+						writer.setSelectionAttribute( 'highlight', highlighter );
+					}
+				} else if ( highlighter ) {
+					writer.setSelectionAttribute( 'highlight', highlighter );
+				}
+			} else {
+				const ranges = model.schema.getValidRanges( selection.getRanges(), 'highlight' );
+
+				for ( const range of ranges ) {
+					if ( highlighter ) {
+						writer.setAttribute( 'highlight', highlighter, range );
+					} else {
+						writer.removeAttribute( 'highlight', range );
+					}
+				}
+			}
+		} );
+	}
+}
diff --git a/packages/ckeditor5-highlight/src/highlightediting.ts b/packages/ckeditor5-highlight/src/highlightediting.ts
new file mode 100644
index 00000000000..9c4d26327c0
--- /dev/null
+++ b/packages/ckeditor5-highlight/src/highlightediting.ts
@@ -0,0 +1,139 @@
+/**
+ * @license Copyright (c) 2003-2023, CKSource Holding sp. z o.o. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/**
+ * @module highlight/highlightediting
+ */
+
+import { Plugin, type Editor } from 'ckeditor5/src/core';
+
+import HighlightCommand from './highlightcommand';
+import type { HighlightOption } from './highlight';
+
+/**
+ * The highlight editing feature. It introduces the {@link module:highlight/highlightcommand~HighlightCommand command} and the `highlight`
+ * attribute in the {@link module:engine/model/model~Model model} which renders in the {@link module:engine/view/view view}
+ * as a `<mark>` element with a `class` attribute (`<mark class="marker-green">...</mark>`) depending
+ * on the {@link module:highlight/highlight~HighlightConfig configuration}.
+ */
+export default class HighlightEditing extends Plugin {
+	/**
+	 * @inheritDoc
+	 */
+	public static get pluginName(): 'HighlightEditing' {
+		return 'HighlightEditing';
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	constructor( editor: Editor ) {
+		super( editor );
+
+		editor.config.define( 'highlight', {
+			options: [
+				{
+					model: 'yellowMarker',
+					class: 'marker-yellow',
+					title: 'Yellow marker',
+					color: 'var(--ck-highlight-marker-yellow)',
+					type: 'marker'
+				},
+				{
+					model: 'greenMarker',
+					class: 'marker-green',
+					title: 'Green marker',
+					color: 'var(--ck-highlight-marker-green)',
+					type: 'marker'
+				},
+				{
+					model: 'pinkMarker',
+					class: 'marker-pink',
+					title: 'Pink marker',
+					color: 'var(--ck-highlight-marker-pink)',
+					type: 'marker'
+				},
+				{
+					model: 'blueMarker',
+					class: 'marker-blue',
+					title: 'Blue marker',
+					color: 'var(--ck-highlight-marker-blue)',
+					type: 'marker'
+				},
+				{
+					model: 'redPen',
+					class: 'pen-red',
+					title: 'Red pen',
+					color: 'var(--ck-highlight-pen-red)',
+					type: 'pen'
+				},
+				{
+					model: 'greenPen',
+					class: 'pen-green',
+					title: 'Green pen',
+					color: 'var(--ck-highlight-pen-green)',
+					type: 'pen'
+				}
+			]
+		} );
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public init(): void {
+		const editor = this.editor;
+
+		// Allow highlight attribute on text nodes.
+		editor.model.schema.extend( '$text', { allowAttributes: 'highlight' } );
+
+		const options = editor.config.get( 'highlight.options' )!;
+
+		// Set-up the two-way conversion.
+		editor.conversion.attributeToElement( _buildDefinition( options ) );
+
+		editor.commands.add( 'highlight', new HighlightCommand( editor ) );
+	}
+}
+
+/**
+ * Converts the options array to a converter definition.
+ *
+ * @param options An array with configured options.
+ */
+function _buildDefinition( options: Array<HighlightOption> ): HighlightConverterDefinition {
+	const definition: HighlightConverterDefinition = {
+		model: {
+			key: 'highlight',
+			values: []
+		},
+		view: {}
+	};
+
+	for ( const option of options ) {
+		definition.model.values.push( option.model );
+		definition.view[ option.model ] = {
+			name: 'mark',
+			classes: option.class
+		};
+	}
+
+	return definition;
+}
+
+type HighlightConverterDefinition = {
+	model: { key: string; values: Array<string> };
+	view: Record<string, { name: string; classes: string }>;
+};
+
+declare module '@ckeditor/ckeditor5-core' {
+	interface CommandsMap {
+		highlight: HighlightCommand;
+	}
+
+	interface PluginsMap {
+		[ HighlightEditing.pluginName ]: HighlightEditing;
+	}
+}
diff --git a/packages/ckeditor5-highlight/src/highlightui.ts b/packages/ckeditor5-highlight/src/highlightui.ts
new file mode 100644
index 00000000000..fbde64d1361
--- /dev/null
+++ b/packages/ckeditor5-highlight/src/highlightui.ts
@@ -0,0 +1,282 @@
+/**
+ * @license Copyright (c) 2003-2023, CKSource Holding sp. z o.o. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/**
+ * @module highlight/highlightui
+ */
+
+import { Plugin, icons } from 'ckeditor5/src/core';
+import {
+	ButtonView,
+	SplitButtonView,
+	ToolbarSeparatorView,
+	createDropdown,
+	addToolbarToDropdown,
+	type DropdownView
+} from 'ckeditor5/src/ui';
+
+import markerIcon from './../theme/icons/marker.svg';
+import penIcon from './../theme/icons/pen.svg';
+import type { HighlightOption } from './highlight';
+
+import './../theme/highlight.css';
+
+/**
+ * The default highlight UI plugin. It introduces:
+ *
+ * * The `'highlight'` dropdown,
+ * * The `'removeHighlight'` and `'highlight:*'` buttons.
+ *
+ * The default configuration includes the following buttons:
+ *
+ * * `'highlight:yellowMarker'`
+ * * `'highlight:greenMarker'`
+ * * `'highlight:pinkMarker'`
+ * * `'highlight:blueMarker'`
+ * * `'highlight:redPen'`
+ * * `'highlight:greenPen'`
+ *
+ * See the {@link module:highlight/highlight~HighlightConfig#options configuration} to learn more
+ * about the defaults.
+ */
+export default class HighlightUI extends Plugin {
+	/**
+	 * Returns the localized option titles provided by the plugin.
+	 *
+	 * The following localized titles corresponding with default
+	 * {@link module:highlight/highlight~HighlightConfig#options} are available:
+	 *
+	 * * `'Yellow marker'`,
+	 * * `'Green marker'`,
+	 * * `'Pink marker'`,
+	 * * `'Blue marker'`,
+	 * * `'Red pen'`,
+	 * * `'Green pen'`.
+	 */
+	public get localizedOptionTitles(): Record<string, string> {
+		const t = this.editor.t;
+
+		return {
+			'Yellow marker': t( 'Yellow marker' ),
+			'Green marker': t( 'Green marker' ),
+			'Pink marker': t( 'Pink marker' ),
+			'Blue marker': t( 'Blue marker' ),
+			'Red pen': t( 'Red pen' ),
+			'Green pen': t( 'Green pen' )
+		};
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public static get pluginName(): 'HighlightUI' {
+		return 'HighlightUI';
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public init(): void {
+		const options = this.editor.config.get( 'highlight.options' )!;
+
+		for ( const option of options ) {
+			this._addHighlighterButton( option );
+		}
+
+		this._addRemoveHighlightButton();
+
+		this._addDropdown( options );
+	}
+
+	/**
+	 * Creates the "Remove highlight" button.
+	 */
+	private _addRemoveHighlightButton(): void {
+		const t = this.editor.t;
+		const command = this.editor.commands.get( 'highlight' )!;
+
+		this._addButton( 'removeHighlight', t( 'Remove highlight' ), icons.eraser, null, button => {
+			button.bind( 'isEnabled' ).to( command, 'isEnabled' );
+		} );
+	}
+
+	/**
+	 * Creates a toolbar button from the provided highlight option.
+	 */
+	private _addHighlighterButton( option: HighlightOption ) {
+		const command = this.editor.commands.get( 'highlight' )!;
+
+		// TODO: change naming
+		this._addButton( 'highlight:' + option.model, option.title, getIconForType( option.type ), option.model, decorateHighlightButton );
+
+		function decorateHighlightButton( button: ButtonView ) {
+			button.bind( 'isEnabled' ).to( command, 'isEnabled' );
+			button.bind( 'isOn' ).to( command, 'value', value => value === option.model );
+			button.iconView.fillColor = option.color;
+			button.isToggleable = true;
+		}
+	}
+
+	/**
+	 * Internal method for creating highlight buttons.
+	 *
+	 * @param name The name of the button.
+	 * @param label The label for the button.
+	 * @param icon The button icon.
+	 * @param value The `value` property passed to the executed command.
+	 * @param decorateButton A callback getting ButtonView instance so that it can be further customized.
+	 */
+	private _addButton( name: string, label: string, icon: string, value: string | null, decorateButton: ( button: ButtonView ) => void ) {
+		const editor = this.editor;
+
+		editor.ui.componentFactory.add( name, locale => {
+			const buttonView = new ButtonView( locale );
+
+			const localized = this.localizedOptionTitles[ label ] ? this.localizedOptionTitles[ label ] : label;
+
+			buttonView.set( {
+				label: localized,
+				icon,
+				tooltip: true
+			} );
+
+			buttonView.on( 'execute', () => {
+				editor.execute( 'highlight', { value } );
+				editor.editing.view.focus();
+			} );
+
+			// Add additional behavior for buttonView.
+			decorateButton( buttonView );
+
+			return buttonView;
+		} );
+	}
+
+	/**
+	 * Creates the split button dropdown UI from the provided highlight options.
+	 */
+	private _addDropdown( options: Array<HighlightOption> ) {
+		const editor = this.editor;
+		const t = editor.t;
+		const componentFactory = editor.ui.componentFactory;
+
+		const startingHighlighter = options[ 0 ];
+
+		const optionsMap = options.reduce( ( retVal, option ) => {
+			retVal[ option.model ] = option;
+
+			return retVal;
+		}, {} as Record<string, HighlightOption> );
+
+		componentFactory.add( 'highlight', locale => {
+			const command = editor.commands.get( 'highlight' )!;
+			const dropdownView = createDropdown( locale, SplitButtonView );
+			const splitButtonView = dropdownView.buttonView as HighlightSplitButtonView;
+
+			splitButtonView.set( {
+				label: t( 'Highlight' ),
+				tooltip: true,
+				// Holds last executed highlighter.
+				lastExecuted: startingHighlighter.model,
+				// Holds current highlighter to execute (might be different then last used).
+				commandValue: startingHighlighter.model,
+				isToggleable: true
+			} );
+
+			// Dropdown button changes to selection (command.value):
+			// - If selection is in highlight it get active highlight appearance (icon, color) and is activated.
+			// - Otherwise it gets appearance (icon, color) of last executed highlight.
+			splitButtonView.bind( 'icon' ).to( command, 'value', value => getIconForType( getActiveOption( value, 'type' ) ) );
+			splitButtonView.bind( 'color' ).to( command, 'value', value => getActiveOption( value, 'color' ) );
+			splitButtonView.bind( 'commandValue' ).to( command, 'value', value => getActiveOption( value, 'model' ) );
+			splitButtonView.bind( 'isOn' ).to( command, 'value', value => !!value );
+
+			splitButtonView.delegate( 'execute' ).to( dropdownView );
+
+			// Create buttons array.
+			const buttonsCreator = () => {
+				const buttons = options.map( option => {
+					// Get existing highlighter button.
+					const buttonView = componentFactory.create( 'highlight:' + option.model );
+
+					// Update lastExecutedHighlight on execute.
+					this.listenTo( buttonView, 'execute', () => {
+						( dropdownView.buttonView as HighlightSplitButtonView ).set( { lastExecuted: option.model } );
+					} );
+
+					return buttonView;
+				} );
+
+				// Add separator and eraser buttons to dropdown.
+				buttons.push( new ToolbarSeparatorView() );
+				buttons.push( componentFactory.create( 'removeHighlight' ) );
+
+				return buttons;
+			};
+
+			// Make toolbar button enabled when any button in dropdown is enabled before adding separator and eraser.
+			dropdownView.bind( 'isEnabled' ).to( command, 'isEnabled' );
+
+			addToolbarToDropdown( dropdownView, buttonsCreator, {
+				enableActiveItemFocusOnDropdownOpen: true,
+				ariaLabel: t( 'Text highlight toolbar' )
+			} );
+			bindToolbarIconStyleToActiveColor( dropdownView );
+
+			// Execute current action from dropdown's split button action button.
+			splitButtonView.on( 'execute', () => {
+				editor.execute( 'highlight', { value: splitButtonView.commandValue } );
+			} );
+
+			// Focus the editable after executing the command.
+			// It overrides a default behaviour where the focus is moved to the dropdown button (#12125).
+			this.listenTo( dropdownView, 'execute', () => {
+				editor.editing.view.focus();
+			} );
+
+			/**
+			 * Returns active highlighter option depending on current command value.
+			 * If current is not set or it is the same as last execute this method will return the option key (like icon or color)
+			 * of last executed highlighter. Otherwise it will return option key for current one.
+			 */
+			function getActiveOption<Key extends keyof HighlightOption>( current: string | undefined, key: Key ): HighlightOption[ Key ] {
+				const whichHighlighter = !current ||
+				current === splitButtonView.lastExecuted ? splitButtonView.lastExecuted : current;
+
+				return optionsMap[ whichHighlighter! ][ key ];
+			}
+
+			return dropdownView;
+		} );
+	}
+}
+
+/**
+ * Extends split button icon style to reflect last used button style.
+ */
+function bindToolbarIconStyleToActiveColor( dropdownView: DropdownView ): void {
+	const actionView = ( dropdownView.buttonView as HighlightSplitButtonView ).actionView;
+
+	actionView.iconView.bind( 'fillColor' ).to( ( dropdownView.buttonView! as HighlightSplitButtonView ), 'color' );
+}
+
+/**
+ * Returns icon for given highlighter type.
+ */
+function getIconForType( type: 'marker' | 'pen' ) {
+	return type === 'marker' ? markerIcon : penIcon;
+}
+
+type HighlightSplitButtonView = SplitButtonView & {
+	lastExecuted: string;
+	commandValue: string;
+	color: string;
+};
+
+declare module '@ckeditor/ckeditor5-core' {
+	interface PluginsMap {
+		[ HighlightUI.pluginName ]: HighlightUI;
+	}
+}
diff --git a/packages/ckeditor5-highlight/src/index.ts b/packages/ckeditor5-highlight/src/index.ts
new file mode 100644
index 00000000000..ef13f1557b0
--- /dev/null
+++ b/packages/ckeditor5-highlight/src/index.ts
@@ -0,0 +1,12 @@
+/**
+ * @license Copyright (c) 2003-2023, CKSource Holding sp. z o.o. All rights reserved.
+ * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
+ */
+
+/**
+ * @module highlight
+ */
+
+export { default as Highlight } from './highlight';
+export { default as HighlightEditing } from './highlightediting';
+export { default as HighlightUI } from './highlightui';
diff --git a/packages/ckeditor5-highlight/tsconfig.json b/packages/ckeditor5-highlight/tsconfig.json
new file mode 100644
index 00000000000..9d4c891939c
--- /dev/null
+++ b/packages/ckeditor5-highlight/tsconfig.json
@@ -0,0 +1,7 @@
+{
+  "extends": "ckeditor5/tsconfig.json",
+  "include": [
+    "src",
+    "../../typings"
+  ]
+}
diff --git a/packages/ckeditor5-highlight/tsconfig.release.json b/packages/ckeditor5-highlight/tsconfig.release.json
new file mode 100644
index 00000000000..6d2d43909f9
--- /dev/null
+++ b/packages/ckeditor5-highlight/tsconfig.release.json
@@ -0,0 +1,10 @@
+{
+  "extends": "../../tsconfig.release.json",
+  "include": [
+    "./src/",
+    "../../typings/"
+  ],
+  "exclude": [
+    "./tests/"
+  ]
+}