The ginger tom was found on the bus when it arrived in Newcastle and was undergoing maintenance.
The coach had begun its journey in Pickering in the North York Moors, and later made a stop at Leeming Bar off the A1.
The cat is now being cared for by Cats Protection at their centre in Gildersome, near Leeds, and staff have named him Wendall - the German word for 'traveller'.
He is not microchipped so his owners cannot be traced.
Deputy manager Catherine Hubbard said:
“We are appealing far and wide in the hope that Wendall’s original owners see this plea and come forward. If we haven’t heard from them by Thursday March 29, we’ll be looking to re-home Wendall, so we urge anyone who recognises him to get in touch. As he was not microchipped, we have no way of tracing his owners.”
Contact the centre on 03000 121 505.