Designed for use against aircraft and ground targets, it was effective against light tanks; its armour-piercing round could penetrate 30 millimeters of armour at 500 meters.

This gun was widely employed by the Regia Marina as a deck-mounted anti-aircraft weapon in most Italian warships, in both single and twin mountings; considered a fairly efficient weapon, in the widespread Model 1935 twin mounting, it shared with the similar Cannone-Mitragliera da 37/54 the operating systems and therefore its flaws, namely high vibrations and the requirement for a strong supporting structure.

It was initially fitted in four Panzer Is converted during the Spanish Civil War, by the Nationalists, in an effort to improve their fighting capability against the Soviet T-26s fielded by the Republican forces.

After the Winter War had begun, Finland bought 88 Breda guns from Italy, the last arriving during the Interim Peace in June 1940.

In addition, the four Italian-built Jymy class motor torpedo boats operated by the Finnish Navy each had one 20 mm Breda cannon on the rear deck.

The Finnish Defence Forces used the 20 ItK/35 Breda, as the gun was officially known in that service, as a training weapon for anti-aircraft crews for several decades after the end of World War II.