The Republic of Korea Air Force (Hankook Kong Goon) was one of the largest operators of the Freedom Fighter, receiving 88 F-5As, 30 F-5Bs, and 8 RF-5As.
The first F-5s arrived in Korea in early April of 1965. 16 F-5As and four F-5Bs re-equipped the 105th Fighter Squadron of the 10th Fighter Wing based at Suwon, which achieved operational status on September 1, replacing F-86F Sabres. Another 14 F-5As were delivered to the 102nd FS, also based at Suwon.
The RF-5As equipped a single squadron, and this unit continued to fly the RF-5A some time after the F-5A/F-5B had been replaced by the F-5E/F.
At one point, the F-5 also equipped the Suwon-based "Black Eagles" aerobatic team.
With the situation growing desperate for the government of South Vietnam, in 1972, Korea transferred 36 F-5As and all its RF-5As to the South Vietnamese Air Force. This was essentially a favor to the United States government, with the US government making up the difference by replacing them with F-4s and later-model F-5Es. After the fall of South Vietnam, 19 former Vietnamese F-5As (which had escaped) and two ex-USAF F-5As were handed over to the RoKAF.
During the late 1970s and early 1980s, the F-5A and F-5B were replaced in front-line service with the RoKAF by later-model F-5Es and Fs. By the end of the 1980s, all of the F-5A and F-5B Freedom Fighters were out of RoKAF service.
The RoKAF had originally planned to acquire the RF-4E for reconnaissance purposes, but this plan was abandoned and several F-5As were converted to RF-5A reconnaissance configuration with camera noses. These RF-5As were withdrawn from use in 1990 following the arrival of a second batch of RF-4Cs. This marked the last of Korea's early-model F-5s.