add_action('admin_head', 'my_custom_logo');
 
function my_custom_logo() {
   echo '
      <style type="text/css">
         #header-logo { background-image: url('.get_bloginfo('template_directory').'/images/your-logo.jpg) !important; }
      </style>
   ';
}

Add the following lines of code to your theme's function.php file.

Add your own Logo to Wordpress Dashboard

wordpress

PHP