Following World War II, Whitmore appeared on Broadway in the role of the sergeant in "Command Decision." Metro-Goldwyn-Mayer gave Whitmore a contract, but his role in the film adaptation was played by Van Johnson. His first major picture for MGM was "Battleground," in a role that was turned down by Spencer Tracy, to whom Whitmore bore a noted physical resemblance. He was nominated for the Academy Award for Best Supporting Actor for this role, and won the Golden Globe Award as Best Performance by an Actor In A Supporting Role. Other major films included "Angels in the Outfield," "The Asphalt Jungle", "The Next Voice You Hear", "Above and Beyond", "Kiss Me, Kate", "Them!", "Oklahoma!", "Black Like Me", "Guns of the Magnificent Seven", "Tora! Tora! Tora!", and "Give 'em Hell, Harry!", a one-man show for which Whitmore was nominated for the Academy Award for Best Actor for his portrayal of former U.S. President Harry S Truman. In the film "Tora! Tora! Tora!", he played Admiral William F. "Bull" Halsey.