The 71-year-old victim was struck while waiting for the B4 bus at Bay Ridge Parkway and 13th Avenue just before 12:30 p.m.
He was sitting on the bench at the bus stop when he was struck.
He was taken to Lutheran Medical Center in critical condition.
The pickup truck and a minivan collided at the nearby intersection. The force of the collision sent the pickup truck into the bus stop.
The driver stopped at the scene. Detectives are investigating to find out which vehicle may have run a red light. So far, no charges were immediately filed.