Joe Kennedy was born on July 25, 1915, in Brookline, Massachusetts. He graduated from Harvard College in Cambridge, Massachusetts, in 1938 and was attending Harvard Law School when he dropped out to join the Naval Aviation Cadet Program in June 1941. Kennedy was commissioned an Ensign in the U.S. Navy and designated a Naval Aviator in May 1942. He flew anti-submarine patrols in the Caribbean before being sent to England to fly PB4Y Liberators with the British Naval Command in September 1943. After completing 25 combat missions, Kennedy volunteered for an Operation Aphrodite mission to destroy German V-3 supergun sites, where he was to fly a converted B-24 Liberator to altitude and then parachute out, allowing the aircraft to be remote-controlled to its target. Joseph Kennedy was killed when the BQ-8 (the converted B-24) he was piloting detonated prematurely over England on August 12, 1944. His remains were never recovered. The destroyer USS Joseph P. Kennedy, Jr. (DD-850) was named in his honor and was commissioned on December 15, 1945.

His Navy Cross Citation reads:

For extraordinary heroism and courage in aerial flight as pilot of a United States Liberator bomber on August 12, 1944. Well knowing the extreme dangers involved and totally unconcerned for his own safety, Lieutenant Kennedy unhesitatingly volunteered to conduct an exceptionally hazardous and special operational mission. Intrepid and daring in his tactics and with unwavering confidence in the vital importance of his task, he willingly risked his life in the supreme measure of service and, by his great personal valor and fortitude in carrying out a perilous undertaking, sustained and enhanced the finest traditions of the United States Naval Service.