Just after 3am on Tuesday the 4th of June, the victim was on the bus when a man boarded and sat with his feet on the seats.
The victim, a man in his 50s, confronted the suspect and during a brief struggle was stabbed a number of times in the leg.
The suspect left the bus at East Croydon train station.
Anyone with information on his whereabouts is urged to contact police on 101.
