https://iandunn.name/2013/12/28/programmatically-sign-on-a-wordpress-user/ $user_id = 12345; $user = get_user_by( 'id', $user_id ); if( $user ) { wp_set_current_user( $user_id, $user->user_login ); wp_set_auth_cookie( $user_id ); do_action( 'wp_login', $user->user_login ); }