diff --git a/inc/class-rest-api.php b/inc/class-rest-api.php
index bb65bf2..a28759d 100644
--- a/inc/class-rest-api.php
+++ b/inc/class-rest-api.php
@@ -7,6 +7,12 @@
 
 namespace Big_Bite\themer;
 
+use WP_Error;
+use WP_Theme_JSON;
+use WP_REST_Request;
+use WP_REST_Response;
+use WP_Theme_JSON_Resolver;
+
 /**
  * Custom REST routes.
  */
@@ -33,26 +39,53 @@ public function register_routes() {
 				},
 			)
 		);
+
+		register_rest_route(
+			'themer/v1',
+			'/export',
+			array(
+				'methods'             => 'GET',
+				'callback'            => array( $this, 'get_theme_json' ),
+				'permission_callback' => fn() => is_user_logged_in() && current_user_can( 'edit_theme_options' ),
+			)
+		);
 	}
 
 	/**
 	 * Get custom CSS rules by merging styles from request with existing theme.json data
 	 *
-	 * @param \WP_REST_Request $request Full data about the request.
-	 * @return \WP_REST_Response|\WP_Error theme.json generated stylesheet response data or WP_Error on failure.
+	 * @param WP_REST_Request $request Full data about the request.
+	 * @return WP_REST_Response|WP_Error theme.json generated stylesheet response data or WP_Error on failure.
 	 */
-	public function get_styles( \WP_REST_Request $request ) {
-		$existing_theme_json = \WP_Theme_JSON_Resolver::get_merged_data();
+	public function get_styles( WP_REST_Request $request ) {
+		$existing_theme_json = WP_Theme_JSON_Resolver::get_merged_data();
 
-		if ( ! $existing_theme_json instanceof \WP_Theme_JSON ) {
-			return new \WP_Error( 'no_theme_json', __( 'Unable to locate existing theme.json data', 'themer' ) );
+		if ( ! $existing_theme_json instanceof WP_Theme_JSON ) {
+			return new WP_Error( 'no_theme_json', __( 'Unable to locate existing theme.json data', 'themer' ) );
 		}
 
 		$custom_styles          = $request->get_json_params();
 		$custom_theme_json_data = array_merge( $existing_theme_json->get_raw_data(), $custom_styles );
-		$custom_theme_json      = new \WP_Theme_JSON( $custom_theme_json_data );
+		$custom_theme_json      = new WP_Theme_JSON( $custom_theme_json_data );
 
 		return rest_ensure_response( $custom_theme_json->get_stylesheet() );
 	}
 
+	/**
+	 * Returns an updated theme.json with merged and flattened layers
+	 *
+	 * @return WP_REST_Response|WP_Error
+	 */
+	public function get_theme_json(): WP_REST_Response | WP_Error {
+		$all_theme_json_layers = WP_Theme_JSON_Resolver::get_merged_data();
+
+		if ( ! $all_theme_json_layers instanceof WP_Theme_JSON ) {
+			return new WP_Error( 'no_theme_json', __( 'Unable to locate existing theme.json data', 'themer' ) );
+		}
+
+		$theme_json_raw_data  = new WP_Theme_JSON( $all_theme_json_layers->get_raw_data() );
+		$theme_json_flattened = $theme_json_raw_data->get_data();
+
+		return rest_ensure_response( $theme_json_flattened );
+	}
 }
diff --git a/src/editor/components/ButtonExport.js b/src/editor/components/ButtonExport.js
new file mode 100644
index 0000000..c5fbcad
--- /dev/null
+++ b/src/editor/components/ButtonExport.js
@@ -0,0 +1,62 @@
+import { __ } from '@wordpress/i18n';
+import apiFetch from '@wordpress/api-fetch';
+import { useState } from '@wordpress/element';
+import { Button } from '@wordpress/components';
+
+/**
+ * Renders the button to export theme.json
+ */
+const ButtonExport = () => {
+	const [ isFetching, setIsFetching ] = useState( false );
+	const isExportSupported =
+		window.isSecureContext && 'showSaveFilePicker' in window;
+
+	/**
+	 * Fetch theme JSON object
+	 */
+	const fetchThemeJSON = async () => {
+		setIsFetching( true );
+		try {
+			const response = await apiFetch( { path: '/themer/v1/export' } );
+			saveThemeJSON( JSON.stringify( response, null, '\t' ) );
+		} catch ( error ) {
+			console.error( error ); // eslint-disable-line no-console -- Output of caught error
+		}
+		setIsFetching( false );
+	};
+
+	/**
+	 * Save JSON blob to a file
+	 *
+	 * @param {Object} data theme.json data
+	 */
+	const saveThemeJSON = async ( data ) => {
+		const blob = new Blob( [ data ], { type: 'application/json' } ); // eslint-disable-line no-undef -- Blob available in browser environment
+
+		const handle = await window.showSaveFilePicker( {
+			suggestedName: 'theme.json',
+		} );
+		const stream = await handle.createWritable();
+
+		await stream.write( blob );
+		await stream.close();
+	};
+
+	if ( ! isExportSupported ) {
+		return;
+	}
+
+	return (
+		<Button
+			isPrimary
+			isBusy={ isFetching }
+			disabled={ isFetching }
+			onClick={ fetchThemeJSON }
+			aria-label={ __( 'Export theme.json', 'themer' ) }
+		>
+			{ __( 'Export theme.json', 'themer' ) }
+		</Button>
+	);
+};
+
+export default ButtonExport;
diff --git a/src/editor/components/fields/ThemerComponent.js b/src/editor/components/fields/ThemerComponent.js
index 0fb8f1f..882f273 100644
--- a/src/editor/components/fields/ThemerComponent.js
+++ b/src/editor/components/fields/ThemerComponent.js
@@ -6,6 +6,7 @@ import apiFetch from '@wordpress/api-fetch';
 
 import Preview from './Preview';
 import Fields from './Fields';
+import ButtonExport from '../ButtonExport';
 
 /**
  * main component
@@ -123,6 +124,7 @@ const ThemerComponent = () => {
 						onClick={ () => reset() }
 						text="reset to theme.json"
 					/>
+					<ButtonExport />
 				</div>
 				<div className="themer-fields">
 					<Fields sourceObject={ themeConfig } />