The Mitsubishi Ki-1 was also designated Mitsubishi Army Type 93-I Heavy Bomber under the long aircraft nomenclature system used by the Japanese military. Already obsolete by the time of its introduction, it found use during the counterinsurgency operations of the Pacification of Manchukuo, as well as limited use during the Second Sino-Japanese War.
The design was upgraded to the Mitsubishi Ki-1-II (Mitsubishi Army Type 93-II Heavy Bomber) with a strengthened airframe and slightly more powerful 723 hp (539 kW) Mitsubishi Ha2-III V-12 engines, which increased maximum speed to 230 km/h (140 mph). However, even with the new engines, the Ki-1 was still underpowered, and was unable to maintain altitude during single engine flights, which proved to be a serious issue during the aircraft's operational service due to lack of reliability of the engines. It was replaced in 1937 by the Fiat BR.20.