Callers to police reported the boy was struck in the face and pushed by a man, who appeared to be the only caregiver present.
Police said the man then got on the bus and left the child at the bus stop near the corner of 152 Street and 64 Avenue.
A witness took the boy to a store across the street while police were called. A number of people tweeted the boy's picture on social media in an attempt to find his mother.
Surrey RCMP Staff Sgt. M.A. Henderson said police have identified the boy and re-united him with his mother.
Henderson said a suspect has been arrested in connection with the assault and abandonment of a young child. Police released no further information on the individual's relationship, if any, to the child.