When the Korean War began on 25 June 1950, USS Valley Forge was in the South China Sea. After moving north, she began air attacks on 3 July and continued on the 4th, hitting airfields and other facilities in western North Korea. Early combat operations were restricted by ammunition shortages and a need to protect the Taiwan Strait, so her next series of strikes did not begin until 18 July. Thereafter, Valley Forge regularly launched her planes against enemy targets, both for close air support of troops on the ground and to attack North Korean communications and structures beyond the front lines.

For the war's first month, Valley Forge was the only U.S. carrier in the war zone, though her efforts were much assisted by the British light carrier HMS Triumph. In late July and early August another U.S. fleet carrier and two escort carriers arrived, giving the hard-working "Happy Valley" badly needed support and relief. She continued war operations until 19 November 1950, flying a deployment total of over 5000 combat sorties and delivering some 2000 tons of ordnance. Her first war tour completed, Valley Forge steamed back to the U.S. for overhaul, arriving at San Diego on 1 December.