diff --git a/packages/php/email-editor/src/Engine/class-user-theme.php b/packages/php/email-editor/src/Engine/class-user-theme.php
new file mode 100644
index 0000000000..7bccb89ae0
--- /dev/null
+++ b/packages/php/email-editor/src/Engine/class-user-theme.php
@@ -0,0 +1,95 @@
+<?php
+/**
+ * This file is part of the MailPoet Email Editor package.
+ *
+ * @package MailPoet\EmailEditor
+ */
+
+declare(strict_types = 1);
+namespace MailPoet\EmailEditor\Engine;
+
+use WP_Post;
+use WP_Theme_JSON;
+
+/**
+ * This class is responsible for managing and accessing theme data aka email styles created by users.
+ */
+class User_Theme {
+	private const USER_THEME_POST_NAME = 'wp-global-styles-mailpoet-email';
+	private const INITIAL_THEME_DATA   = array(
+		'version'                     => 3,
+		'isGlobalStylesUserThemeJSON' => true,
+	);
+
+	/**
+	 * Core theme loaded from the WordPress core.
+	 *
+	 * @var WP_Post | null
+	 */
+	private ?WP_Post $user_theme_post = null;
+
+	/**
+	 * Getter for user theme.
+	 *
+	 * @throws \Exception If the user theme post cannot be created.
+	 * @return WP_Theme_JSON
+	 */
+	public function get_theme(): WP_Theme_JSON {
+		$post       = $this->get_user_theme_post();
+		$theme_data = json_decode( $post->post_content, true );
+		if ( ! is_array( $theme_data ) ) {
+			$theme_data = self::INITIAL_THEME_DATA;
+		}
+		return new WP_Theme_JSON( $theme_data, 'custom' );
+	}
+
+	/**
+	 * Getter for user theme post.
+	 * If the post does not exist, it will be created.
+	 *
+	 * @throws \Exception If the user theme post cannot be created.
+	 * @return WP_Post
+	 */
+	public function get_user_theme_post(): WP_Post {
+		$this->ensure_theme_post();
+		if ( ! $this->user_theme_post instanceof WP_Post ) {
+			throw new \Exception( 'Error creating user theme post' );
+		}
+		return $this->user_theme_post;
+	}
+
+	/**
+	 * Ensures that the user theme post exists and is loaded.
+	 *
+	 * @throws \Exception If the user theme post cannot be created.
+	 */
+	private function ensure_theme_post(): void {
+		if ( $this->user_theme_post ) {
+			return;
+		}
+		$this->user_theme_post = get_page_by_path( self::USER_THEME_POST_NAME, OBJECT, 'wp_global_styles' );
+		if ( $this->user_theme_post instanceof WP_Post ) {
+			return;
+		}
+		$post_data = array(
+			'post_title'   => __( 'Custom Email Styles', 'mailpoet' ),
+			'post_name'    => self::USER_THEME_POST_NAME,
+			'post_content' => (string) wp_json_encode( self::INITIAL_THEME_DATA, JSON_FORCE_OBJECT ),
+			'post_status'  => 'publish',
+			'post_type'    => 'wp_global_styles',
+		);
+
+		/**
+		 * The doc is needed since PHPStan thinks that wp_insert_post can't return WP_Error.
+		 *
+		 * @var int|\WP_Error $post_id
+		 */
+		$post_id = wp_insert_post( $post_data );
+
+		if ( is_wp_error( $post_id ) ) {
+			throw new \Exception( 'Error creating user theme post: ' . esc_html( $post_id->get_error_message() ) );
+		}
+
+		$this->user_theme_post = get_post( $post_id );
+	}
+}
diff --git a/packages/php/email-editor/tests/integration/Engine/User_Theme_Test.php b/packages/php/email-editor/tests/integration/Engine/User_Theme_Test.php
new file mode 100644
index 0000000000..fcb34a6b9e
--- /dev/null
+++ b/packages/php/email-editor/tests/integration/Engine/User_Theme_Test.php
@@ -0,0 +1,87 @@
+<?php
+/**
+ * This file is part of the MailPoet Email Editor package.
+ *
+ * @package MailPoet\EmailEditor
+ */
+
+declare(strict_types = 1);
+namespace MailPoet\EmailEditor\Engine;
+
+/**
+ * Integration test for User Theme class
+ */
+class User_Theme_Test extends \MailPoetTest {
+	/**
+	 * Instance of User_Theme created before each test.
+	 *
+	 * @var User_Theme
+	 */
+	private User_Theme $user_theme;
+
+	/**
+	 * Set up before each test.
+	 */
+	protected function _before(): void {
+		parent::_before();
+		$this->user_theme = new User_Theme();
+	}
+
+	/**
+	 * Test it can create and return a user theme post
+	 */
+	public function testItCreatesUserThemePostLazily(): void {
+		$post = $this->user_theme->get_user_theme_post();
+		$this->assertInstanceOf( \WP_Post::class, $post );
+		$post_content = json_decode( $post->post_content, true );
+		$this->assertIsArray( $post_content );
+		$this->assertArrayHasKey( 'version', $post_content );
+		$this->assertEquals( 3, $post_content['version'] );
+		$this->assertArrayHasKey( 'isGlobalStylesUserThemeJSON', $post_content );
+		$this->assertTrue( $post_content['isGlobalStylesUserThemeJSON'] );
+	}
+
+	/**
+	 * Test it fetches previously stored data
+	 */
+	public function testItFetchesPreviouslyStoredData(): void {
+		$styles_data = array(
+			'version'                     => 3,
+			'isGlobalStylesUserThemeJSON' => true,
+			'styles'                      => array(
+				'color' => array(
+					'background' => '#000000',
+					'text'       => '#ffffff',
+				),
+			),
+		);
+		$post_data   = array(
+			'post_title'   => __( 'Custom Email Styles', 'mailpoet' ),
+			'post_name'    => 'wp-global-styles-mailpoet-email',
+			'post_content' => (string) wp_json_encode( $styles_data, JSON_FORCE_OBJECT ),
+			'post_status'  => 'publish',
+			'post_type'    => 'wp_global_styles',
+		);
+		wp_insert_post( $post_data );
+
+		$post = $this->user_theme->get_user_theme_post();
+		$this->assertInstanceOf( \WP_Post::class, $post );
+		$post_content = json_decode( $post->post_content, true );
+		$this->assertIsArray( $post_content );
+		$this->assertArrayHasKey( 'version', $post_content );
+		$this->assertEquals( 3, $post_content['version'] );
+		$this->assertArrayHasKey( 'isGlobalStylesUserThemeJSON', $post_content );
+		$this->assertTrue( $post_content['isGlobalStylesUserThemeJSON'] );
+		$this->assertEquals( $styles_data['styles'], $post_content['styles'] );
+	}
+
+	/**
+	 * Test it returns the user WP_Theme_JSON
+	 */
+	public function testItCreatesThemeJson(): void {
+		$theme = $this->user_theme->get_theme();
+		$this->assertInstanceOf( \WP_Theme_JSON::class, $theme );
+		$raw = $theme->get_raw_data();
+		$this->assertArrayHasKey( 'version', $raw );
+	}
+}
diff --git a/packages/php/email-editor/tests/integration/_bootstrap.php b/packages/php/email-editor/tests/integration/_bootstrap.php
index 0a81e734f9..36c0276d30 100644
--- a/packages/php/email-editor/tests/integration/_bootstrap.php
+++ b/packages/php/email-editor/tests/integration/_bootstrap.php
@@ -28,6 +28,7 @@ use MailPoet\EmailEditor\Engine\Templates\Template_Preview;
 use MailPoet\EmailEditor\Engine\Templates\Templates;
 use MailPoet\EmailEditor\Engine\Templates\Utils;
 use MailPoet\EmailEditor\Engine\Theme_Controller;
+use MailPoet\EmailEditor\Engine\User_Theme;
 use MailPoet\EmailEditor\Integrations\Core\Initializer;
 use MailPoet\EmailEditor\Integrations\MailPoet\Blocks\BlockTypesController;
 use MailPoet\EmailEditor\Engine\Send_Preview_Email;
@@ -170,6 +171,12 @@ abstract class MailPoetTest extends \Codeception\TestCase\Test { // phpcs:ignore
 				return new Theme_Controller();
 			}
 		);
+		$container->set(
+			User_Theme::class,
+			function () {
+				return new User_Theme();
+			}
+		);
 		$container->set(
 			Settings_Controller::class,
 			function ( $container ) {