The 1977 King Cup was the 19th season of the knockout competition since its establishment in 1956. Al-Nassr were the defending champions; however, they were eliminated in the semi-finals by Al-Hilal. The final saw Al-Ahli beat Al-Hilal 3–1, with Al-Ahli scoring all three goals in the final fifteen minutes. Al-Ahli won their seventh title and first since 1973.