Founded as Seversky Aircraft Corporation at Long Island, New York, in 1931. Since de Seversky had made somewhat of a pariah of himself in the USA by selling combat aircraft to Japan, the Army ordered no more P-35s from Seversky. By early 1939, his company had gotten itself into some deep financial trouble. In Apr 1939, while de Seversky was out of the country on a business trip, the board of directors of his company voted him out of office as CEO and changed the name of the company to Republic. The newly-formed company then recapitalized itself and Alexander Kartveli was appointed as vice president and technical director. Having been forced into involuntary early retirement, de Seversky spent the rest of his life writing and consulting, and Kartveli and the Republic company went on to design and produce the famed P-47 Thunderbolt.

Secured $56.5 million contract for fighter from the USAAC in 1940, largest single fighter order ever placed until then by U.S. Government. Built P- 35, P-44 and P-43 Lancers for USAAC plus some EP-1 s, based on P-35, for Swedish Government. Lancer design developed further into P-47 Thunderbolt for USAAF, of which 15,329 were built during Second World War.

Aircooled Motors, manufacturers of the Franklin aircraft engines, were acquired by Republic on 27 December 1945.

Immediate postwar designs included the Seabee single-engine amphibian, the XF-12 high-altitude long-range four-engine photo-reconnaissance aircraft prototype, and the F-84 Thunderjet/Thunderstreak/Thunderflash series of jetfighters. The larger and heavier F-105 Thunderchief followed in 1955, and in 1965 the company became the Republic Aviation Division of Fairchild Hiller Corporation.
Republic became a division of Fairchild in 1965, becoming the Fairchild Republic Company in 1972.