After the Merlin-powered P-63B failed to come to fruition, production moved to the P-63C. It was powered by an improved Allison engine that came equipped with water injection which could boost power up to an impressive 1,800 hp. The wingspan was also shortened but was otherwise largely the same as the P-63A. The C-5 in particular had a ventral fin to help with stability and had more armour. Over 1,000 P-63Cs were produced and delivered well into the war. Many were sent to the Soviets under the lend-lease program but around 100 were also sent to France.

The P-63C-5 has been present since the start of the Open Beta Test prior to Update 1.27. It features a far better engine than the previous P-63A but also retains the four 12.7 mm machine guns and 37 mm cannon mounted through the propeller hub. The Allison V-1710-117 helps the P-63 perform much better at low altitude but high-altitude performance still leaves much to be desired. Players should stick to low-altitude fighting where the Kingcobra shines. For ground attack, the Kingcobra also has three 500 lb bombs, two mounted on either wing and one mounted in the centre. The 37 mm cannon also has access to AP rounds however it's ill-advised to use them against armoured targets due to their low velocity.