Etchebarren was born in Whittier, California of Basque descent. He was signed by the Baltimore Orioles as an amateur free agent in 1961. Expected to be the Orioles' third-string catcher entering his MLB rookie season in 1966, he became the starter in spring training when Dick Brown and Charley Lau underwent surgery to remove a brain tumor and remedy an ailing elbow respectively in the same timeframe. Etchebarren was the last man to bat against Sandy Koufax, when he hit into a double play during the sixth inning of Game 2 of the 1966 World Series. Etchebarren helped the Orioles to win the 1966 and 1970 World Series, 1969 and 1971 AL pennants, and the 1973 and 1974 AL Eastern Division championships.