The first Twin Mustangs began to reach the squadrons during 1948. In June of that year, the P-designation was changed to F, and the Twin Mustang became F-82 rather than P-82. The F-82E entered service in the long-range bomber escort role with the 27th Fighter Group (522nd, 523rd, and 524th Squadrons) of the Strategic Air Command. They spent their brief life flying alongside B-29s, and were replaced by jets in 1950.
In 1948, the F and G night-fighter versions of the Twin Mustang began to replace the Northrop F-61 Black Widow in service with the Air Defense Command. They were painted all-black and had flame-damped exhausts. The first Air Defense Command unit to take delivery of the F-82F was the 325th Fighter Group (317th, 318th, and 319th Squadrons) based at both Hamilton Field, California and McChord AFB, Washington, the 51st Fighter Group (16th, 25th, and 26th Squadrons) and the 52nd Fighter Group (2nd and 5th Squadrons) based at Mitchel AFB and McGuire AFB, New Jersey. In 1949, the 347th Fighter Group (4th, 68th, and 339th Squadrons) stationed in Japan received F-82Gs. The 449th Squadron of the 5001st Composite Group based at Ladd AFB in Alaska received the "cold-weather F-82Hs.
By the middle of 1949, the Twin Mustang was in widespread service, some 225 E, F, and G models being on strength. It was anticipated that the service life of the Twin Mustang would be relatively brief, since the F-82 was seen as only an interim type, filling in the gap only until adequate numbers of jet fighters could be made available. In 1950, some units based in the USA were already beginning to replace their Twin Mustangs with jets.
On June 25, 1950, the Korean War broke out. The Twin Mustangs based in Japan were immediately thrown into combat to stem the North Korean advance. They were the only fighter aircraft available with the range to cover the entire Korean peninsula from bases in Japan. They provided fighter cover for the C-54 and C-47 transports flying in and out of Kimpo Airfield near Seoul. On June 27, 1950, an F-82G (46-383) of the 68th Fighter Squadron of the 347th Fighter Group flown by Lieut. William Hudson (pilot) and Lieut. Carl Fraser (radar operator) shot down a North Korean Yak-7U. This was the first air-to-air kill of the Korean War, and, incidentally, the first aerial victory by the newly-formed United States Air Force. Squadron records have been lost, and memory is unreliable, and it is possible that Lt. Hudson was actually flying 46-601 that day. Later that same day, an F-82G (46-392) flown by Major James Little of the 339th Fighter Squadron of the 347th Fighter Group shot down a North Korean Yak-9. Records are unreliable, and some experts maintain that Major Little actually was the first to kill.
The Twin Mustang saw extensive service in Korea until November of 1951, serving in both escort and ground attack roles. However, the F-82 played a secondary role as compared with its distinguished predecessor, the single-engined F-51. As more jets became available, the F-82s were withdrawn from combat and phased out of service.
The last Twin Mustang was retired from service in mid-1953.