In response to an Army request in 1943 for a 13,344 - 17,792 N (3,000 - 4,000 lb) thrust turbojet, GE proposed the I-40, a centrifugal-flow engine that could be produced in a short time. Service as the J33 began in 1945 on the Lockheed P-80A, America's first operational jet fighter, which was its primary application.

For wartime needs, production was licensed to the Allison division of General Motors. When the war ended, the Army re-evaluated its engine program, and turned over all production to Allison.

The J33 was GE's first turbojet engine of its own design, its last all-centrifugal-flow engine; as well as the last to be used in U.S. military combat aircraft. It powered other first generation jet aircraft including: Martin XB-51; Lockheed XP-81, F-80A/B/C, RF-80A, QF-80F, XF-14/A, TF-80C, T-33A/B, AT-33A, DT-33A/B/C, RT-33A, QT-33A, WT-33A, T-1A; North American F-86C; Northrop F-89J; and Bell XP-83.