Lembeck was born in Brooklyn, New York, the son of Caroline Dubs and Harvey Lembeck, an actor and comedian. He began acting in the late-1960s and directing in the 1970s. His most notable acting role was as Julie Cooper's husband, Max Horvath, on the sitcom, One Day at a Time. He played news caster Clete Meizenheimer on the series, Mary Hartman, Mary Hartman. He also played "Kaptain Kool" of Kaptain Kool and the Kongs on The Krofft Supershow from 1976 to 1978. He is also known for his role as Vinnie Fazio in The Boys in Company C in 1978. He was a member of the cast of the 1985–1986 situation comedy Foley Square.