Police were called at 4pm on Wednesday, 5 May after the driver, a man in his 30s, was found injured outside North Harrow Underground Station.
Officers attended along with London Ambulance Service. It was reported that the driver had been punched by a passenger who he had challenged for not wearing a face mask.
The driver was taken to hospital where he received treatment for a head injury. He has since been discharged and has made a full recovery.
Detectives from the Met’s Roads and Transport Policing Command are investigating and have recovered CCTV from the bus.