VPB-121 was a Patrol Bombing Squadron of the U.S. Navy. The squadron was established as Patrol Squadron 19 (VP-19) on 1 October 1937, redesignated Patrol Squadron 43 (VP-43) on 1 July 1939, redesignated Patrol Squadron 81 (VP-81) on 1 July 1941, redesignated Patrol Bombing Squadron 121 (VPB-121) on 1 October 1944 and disestablished on 1 June 1946.

The squadron was assigned the following aircraft, effective on the dates shown:

The squadron was assigned to these home ports, effective on the dates shown:

This article incorporates text from the public domain Dictionary of American Naval Aviation Squadrons.