Landrum was acquired by the Baltimore Orioles on August 31, 1983, the last day for player postseason eligibility. This was the completion of a transaction from months prior when the Orioles sent Floyd Rayford to the St. Louis Cardinals on June 13. Landrum hit the game-winning home run for the Orioles in the final game of the 1983 American League Championship Series. He was a very late addition to the Orioles post-season roster, and such an unlikely hero that teammate John Lowenstein joked that he was not sure of Landrum's first name.