The UH-1C was specifically developed as a gunship version until the "interim" attack helicopter, the Bell AH-1G Huey Cobra was available and to correct the deficiencies of the UH-1B when it was used in the armed role. The UH-1C was widely referred to as the "Huey Hog" in US Army service.
The "Charlie" model was fitted with the 1,100 shp (820 kW) T53-L-9 or L-11 engine to provide the power needed to lift the weapons systems in use or under development at the time. It incorporated the new Bell 540 rotor system with 27-inch (690 mm) chord blades. The increased power lead Bell's engineers to design a new tailboom for the "C" which incorporated a wider chord fin on a longer boom and larger synchronized elevators. The "C" also introduced a dual hydraulic control system for redundancy in battle and an improved inlet filter system for the dusty conditions found in Southeast Asia. Fuel was increased to 242 US gallons and gross weight to 9,500 lb (4,300 kg), giving a nominal useful load of 4,673 lb (2,120 kg).
Development on the "C" model had commenced in 1960, with production starting in June 1966. A total of 766 "C" models were completed, including five for the Royal Australian Navy and five for Norway. The balance went to the US Army. Many UH-1Cs were later re-engined with the 1,400 shp (1,000 kW) Lycoming T53-L-13 powerplant. With this engine they were redesignated UH-1M.