It happened at 11:40 a.m. Wednesday in Northeast Philadelphia.
Police say the officer was riding east on Cottman Avenue when he was struck by a Lexus turning right from Cottman onto Bustleton Avenue.
The motorist did not stop.
The officer was taken to Aria Health, Torresdale Division where was listed in stable condition with a knee injury.
Police caught up with driver of the Lexus a short time later at Longshore and Castor Avenues.
An investigation is underway.