The J Type was produced from 1932 until 1934 and was derived from the first MG Midget, the M-Type and the short-lived D-Type of 1932. William Morris and Cecil Kimber had founded MG in 1924, and its name was derived from Morris Garages, an Oxford dealer of Morris Automobiles, which later produced its own cars wearing designs by Kimber. The J-Type was powered by an updated Wolsely-derived overhead-cam 847cc Morris Minor motor breathing through twin SU carburetors and delivering 36 horsepower. They had a four-speed gearbox, a simple channel section chassis frame, half-elliptic springing all round, an ash frame, beam axle, and cable-operated 8-inch diameter brakes. Most of the MGs were two-seaters and the design would establish the classic MG appearance that would characterize the Abingdon marque’s sports cars into the 1950s.

Both the J1 and J2 were powered by the single overhead camshaft 847cc engine. The J2 Midget was offered with either sweeping wings or the more popular cycle-type. 2,083 of the Type J2 two-seater versions were produced between mid-1932 and early 1934. The J1 was a four-seater versions available as a closed salonette. The early versions had cycle wings. The J3 and J4 styles were racing version using a 746 cc engine outfitted with a Powerplus supercharger. The J4 was a light-weight version of the J3.

The MG J Type was the predecessor to the P Type, and then the popular T Series.