The incident happened in Surrey Quays Road near Maritime Street at around 5.35pm yesterday (March 11).
Officers and London Ambulance Service crews attended and found the boy injured.
He was taken to hospital in a critical condition, however, his injuries have since been assessed as non-life threatening.
His family have been informed.
A spokesperson for Metropolitan Police said: “At about 5.35pm on Tuesday, 11 March, officers on patrol came upon a bus in collision with a cyclist on Surrey Quays Road.
“Officers, the London Ambulance Service and London’s Air Ambulance attended.
“The cyclist, who is a child, was taken to hospital in a critical condition.
“The child’s condition has now been confirmed to be non-life threatening.
“His family has been informed.”
A spokesperson for London Ambulance Service said: “We were called at 5.36pm yesterday (11 March) to reports of a road traffic collision in Maritime Street, Southwark.
“We sent resources including an ambulance crew, paramedics in fast response cars and an incident response officer to the scene. We also dispatched London’s Air Ambulance.
“We treated a child at the scene and took them to a major trauma centre by road as a priority.”
