The Firefly F Mk I is a British strike aircraft. It was introduced in Update 1.49 "Weapons of Victory".

Within War Thunder, the Firefly F Mk I is a Rank III aircraft situated early on in the Fleet Air Arm line. The distinctive feature of the Firefly Mk I is its characteristic chin radiator that supports the powerful Rolls-Royce Griffon engine, later variants of which can also be seen on the late model Spitfires and Seafire. The aircraft is one of the first examples of a 4 cannon fighter aircraft available to pilots and boasts an impressive array of external weaponry to complement this.

Its 4 x 20 mm Hispano Mk II cannons carry 160 rounds per gun for a total capacity of 640 rounds. This allows pilots of the Firefly to have more opportunities to attack enemy aircraft or ground targets with its guns. However, trigger discipline should still be practiced in order to get the most out of it when it is being operated solely as a fighter. The Firefly can also mount 2 x 250 lb, 2 x 500 lb or 2 x 1,000 lb bombs with one under each wing. The final weapon upgrade, "HRC mk.8", allows for the installation of 8 x 76 mm RP-3 rockets, further boosting its ground attack capabilities.

The Firefly often struggles in initial climbing due to the heavy weight and large size of the aircraft. Once engaged, however, the Firefly's "Ace" combat advantage is its exceptional two stage combat flaps. Unlike most aircraft where the flap simply deploys from the wing, the Firefly's flaps actually swing back to enlarge the wing surface as a whole and create much more lift. This allows it to turn exceptionally well at low speeds without external ordnance attached and makes landings very simple to perform even on carriers. Coupled with a wide track and durable undercarriage, the Firefly rounds off to be a very forgiving aircraft to fly.