The 1966 Idaho gubernatorial election was held on November 8. Republican nominee Don Samuelson defeated Democratic nominee Cecil Andrus with 41.4% of the vote in a four-way race.

Donald William Samuelson was an American Republican politician who served as the 25th governor of Idaho, from 1967 to 1971. He is the state's most recent incumbent governor to lose a re-election bid (1970).