In the Summer of 1941, engineers were evaluating the use of a 40 mm cannon for aircraft use. Two designs were in consideration, the Vickers S and Rolls-Royce BH. To test these cannons, a Beaufighter Mk.I prototype was modified to have the cannons installed in place of its usual 20 mm autocannons. The results of the test went on to select the Vickers S 40 mm cannon for follow up development, which also saw use in the Hurricane Mk IV.

Introduced during Update "Direct Hit" as a reward for Battle Pass: Season V, "River Hunter", the Beaufighter Mk I presents strong firepower for use against air and ground targets. Although this Beaufighter does not carry any suspended ordnance, the 40 mm armed Beaufighter presents enough penetrating power to threaten the weaker armour on tanks. The large calibre explosive power would also allow the Beaufighter to decimate large fighters and bombers. That said, the availability of only large cannons and a single machine gun for self-defense means this plane would not do well against manoeuvrable small fighters.