Known as The Human Joke Machine, Amsterdam began his career as a cellist, then entered vaudeville with his brother. While performing, he penned jokes for such stars as Fanny Brice and Will Rogers, and co-wrote such songs as "Rum and Coca-Cola" and "Why Oh Why Did I Ever Leave Wyoming?". He was also a screenwriter for MGM and for various radio shows. By the late 1940s, Amsterdam was writing gags for himself, appearing on three daily series in 1947 alone (he once did 75 shows in one week). He also wrote political gags for Presidents Roosevelt, Johnson and Reagan.
Amsterdam started in TV early, when his CBS radio series, "The Morey Amsterdam Show" was transferred to the small screen in 1948. He also loaned his talents to such comedy and quiz shows as "Stop Me If You've Heard This One" (NBC, 1948), "Broadway Open House" (NBC, 1950), "Can You Top This?" (ABC, 1950-51), "Battle of the Ages" (CBS, 1952), "Who Said That?" (NBC, 1954) and "Keep Talking" (CBS, 1958-60). Amsterdam made his debut as a dramatic actor on a 1952 segment of "Not for Publication" (Dumont).
But it was "The Dick Van Dyke Show" that brought Amsterdam lasting fame. He and Rose Marie, as Van Dyke's co-workers, brought a fast-paced vaudeville sensibility to the modern suburban sitcom. Insulting Mel (Richard Deacon) or his wife Pickles, or thinking up on-the-spot gags, Buddy Sorrell was a high point of the show. He also one of the first openly Jewish TV characters (in one episode, Buddy treated himself to a belated Bar Mitzvah).
His film career was spotty at best. Amsterdam wrote the screenplay for "The Ghost and the Guest" (1943) and made small appearances in such films as "It Came from Outer Space" (1953), "Machine Gun Kelly" (1958), "Murder, Inc." (1960), "Beach Party" (1963) and "Muscle Beach Party" (1964), and "The Horse in the Gray Flannel Suit" (1968). He also wrote and appeared in the comedy "Don't Worry, We'll Think of a Title" (1966) and had a bit part in the thriller "Sandman" (1992). In later years, Amsterdam appeared on "The Hollywood Squares" (NBC, 1966-81), "Comedy Break" (syndicated, 1985), the daytime soap "The Young and the Restless" (CBS, 1989-90, as a kidnapper), "First and Ten: In Your Face!" (HBO, 1990) and "Comic Relief" (HBO, 1992). He executive produced a 1970 revival of the show "Can You Top This?" (syndicated) and kept busy on the nightclub and college circuit. He was last seen with "Van Dyke" co-star Rose Marie on an episode of NBC's "Caroline in the City" in 1996.