diff --git a/src/wp-admin/css/common.css b/src/wp-admin/css/common.css
index e062a471d7150..4e255a48843fd 100644
--- a/src/wp-admin/css/common.css
+++ b/src/wp-admin/css/common.css
@@ -3572,6 +3572,10 @@ img {
 	line-height: 180%;
 }
 
+.fileedit-sub .download-theme-form {
+	margin-top: 8px;
+}
+
 #file-editor-warning .file-editor-warning-content {
 	margin: 25px;
 }
diff --git a/src/wp-admin/theme-editor.php b/src/wp-admin/theme-editor.php
index 68d6f9a7e966a..72dde4f6709c5 100644
--- a/src/wp-admin/theme-editor.php
+++ b/src/wp-admin/theme-editor.php
@@ -77,6 +77,126 @@
 	wp_die( __( 'The requested theme does not exist.' ) . ' ' . $theme->errors()->get_error_message() );
 }
 
+// Handle theme download action: create a zip of the theme and send it to the browser.
+if ( 'download_theme' === $action ) {
+	if ( ! current_user_can( 'edit_themes' ) ) {
+		wp_die( '<p>' . __( 'Sorry, you are not allowed to download themes for this site.' ) . '</p>' );
+	}
+
+	// Verify nonce.
+	if ( ! check_admin_referer( 'download-theme_' . $stylesheet ) ) {
+		wp_die( '<p>' . __( 'Security check failed.' ) . '</p>' );
+	}
+
+	$theme_dir = $theme->get_stylesheet_directory();
+
+	if ( ! is_dir( $theme_dir ) ) {
+		wp_die( '<p>' . __( 'Theme directory not found.' ) . '</p>' );
+	}
+
+	$zipname = $stylesheet;
+	$version = $theme->get( 'Version' );
+	if ( $version ) {
+		$zipname .= '.' . $version;
+	}
+
+	$tmpfile = get_temp_dir() . DIRECTORY_SEPARATOR . $zipname . '-' . time() . '.zip';
+
+	// Attempt to extend execution time to allow large theme archives to be created.
+	if ( function_exists( 'set_time_limit' ) ) {
+		@set_time_limit( 300 );
+	}
+	// Try native ZipArchive first, fall back to PclZip if needed.
+	if ( class_exists( 'ZipArchive' ) ) {
+		$zip = new ZipArchive();
+		if ( true !== $zip->open( $tmpfile, ZipArchive::CREATE ) ) {
+			@unlink( $tmpfile );
+			wp_die( '<p>' . __( 'Could not create zip archive.' ) . '</p>' );
+		}
+
+		$files       = new RecursiveIteratorIterator(
+			new RecursiveDirectoryIterator( $theme_dir, FilesystemIterator::SKIP_DOTS ),
+			RecursiveIteratorIterator::LEAVES_ONLY
+		);
+		$files_added = 0;
+
+		foreach ( $files as $file ) {
+			// With SKIP_DOTS and LEAVES_ONLY, we don't need to check isDir().
+			$file_path = $file->getRealPath();
+
+			// Ensure path is valid and within theme directory.
+			if ( ! $file_path || ! str_starts_with( $file_path, $theme_dir ) ) {
+				continue;
+			}
+
+			$relative_path = substr( $file_path, strlen( $theme_dir ) + 1 );
+
+			if ( ! $zip->addFile( $file_path, $stylesheet . '/' . $relative_path ) ) {
+				$zip->close();
+				@unlink( $tmpfile );
+				wp_die( '<p>' . __( 'Could not create zip archive.' ) . '</p>' );
+			}
+
+			$files_added++;
+		}
+
+		if ( 0 === $files_added ) {
+			$zip->close();
+			@unlink( $tmpfile );
+			wp_die( '<p>' . __( 'No files found to compress.' ) . '</p>' );
+		}
+		$zip->close();
+	} else {
+		// Use PclZip fallback bundled with WordPress admin.
+		require_once ABSPATH . 'wp-admin/includes/class-pclzip.php';
+
+		$filelist = array();
+		$files    = new RecursiveIteratorIterator(
+			new RecursiveDirectoryIterator( $theme_dir, FilesystemIterator::SKIP_DOTS ),
+			RecursiveIteratorIterator::LEAVES_ONLY
+		);
+
+		foreach ( $files as $file ) {
+			$file_path = $file->getRealPath();
+
+			// Ensure path is valid and within theme directory.
+			if ( ! $file_path || ! str_starts_with( $file_path, $theme_dir ) ) {
+				continue;
+			}
+
+			$filelist[] = $file_path;
+		}
+
+		if ( empty( $filelist ) ) {
+			@unlink( $tmpfile );
+			wp_die( '<p>' . __( 'No files found to compress.' ) . '</p>' );
+		}
+
+		$archive = new PclZip( $tmpfile );
+		$result  = $archive->create( $filelist, PCLZIP_OPT_REMOVE_PATH, $theme_dir, PCLZIP_OPT_ADD_PATH, $stylesheet );
+		if ( 0 === $result ) {
+			@unlink( $tmpfile );
+			wp_die( '<p>' . __( 'Could not create zip archive.' ) . ' ' . esc_html( $archive->errorInfo( true ) ) . '</p>' );
+		}
+	}
+
+	if ( ! file_exists( $tmpfile ) ) {
+		@unlink( $tmpfile );
+		wp_die( '<p>' . __( 'Failed to create theme archive.' ) . '</p>' );
+	}
+
+	// Send the file to the browser.
+	header( 'Content-Type: application/zip' );
+	$download_filename = sanitize_file_name( $zipname ) . '.zip';
+	$header_filename   = str_replace( array( '\\\\', '"' ), array( '\\\\\\\\', '\\"' ), $download_filename );
+	header( 'Content-Disposition: attachment; filename="' . $header_filename . '"' );
+	header( 'Content-Length: ' . filesize( $tmpfile ) );
+	readfile( $tmpfile );
+	// Best-effort cleanup of the temporary archive; failure to delete is non-critical.
+	@unlink( $tmpfile );
+	exit;
+}
+
 $allowed_files = array();
 $style_files   = array();
 
@@ -415,6 +535,13 @@
 
 		<?php wp_print_file_editor_templates(); ?>
 	</form>
+
+	<form action="theme-editor.php" method="post" class="download-theme-form">
+		<?php wp_nonce_field( 'download-theme_' . $stylesheet ); ?>
+		<input type="hidden" name="action" value="download_theme" />
+		<input type="hidden" name="theme" value="<?php echo esc_attr( $stylesheet ); ?>" />
+		<?php submit_button( __( 'Download Theme' ), 'secondary', '', false ); ?>
+	</form>
 	<?php
 endif; // End if $error.
 ?>