Most American League World Series Champonships.The New York Yankees won 27 World Series titles, in 40 World Series appearances. More than any other team in Major League history. The Oakland Athletics have the second most World Series titles for an American League team with 9 in 14 World Series appearances. The Boston Red Sox are third with 7 titles in 11 appearances, and the Detroit Tigers are 4th with 4 titles in 10 appearances.