In 1962, Miller made it to his first World Series against the New York Yankees, closing the final innings of Games 1 and 5 while maintaining a 0.00 ERA.
In 1963, the Giants traded Stu Miller along with Mike McCormick to the Baltimore Orioles where Miller would lead the league in Games Played, Games Finished, and Saves. Miller posted a career best 1.89 ERA in 1965 and won a World Series ring as a member of the Orioles the following season. Miller posted ERA's of 2.25 and 2.55 during his final two seasons with the Orioles in 1966 and 1967. He played his final season in the majors with the Atlanta Braves in 1968.