King was the radio voice of the Oakland Athletics baseball team for 25 years (1981–2005), the longest tenure of any A's announcer since the team's games were first broadcast in Philadelphia in 1938, as well as the longtime radio play-by-play announcer for the Oakland/Los Angeles Raiders football team and the San Francisco/Golden State Warriors basketball team. Earlier in his career, he had been a member of the San Francisco Giants' original broadcasting team (together with Russ Hodges and Lon Simmons) when the Giants moved west from New York in 1958, and had called University of California football and basketball games.