The 1909 Detroit Tigers won the American League pennant with a record of 98–54, but lost to the Pittsburgh Pirates in the 1909 World Series, 4 games to 3. The season was their ninth since they were charter members of the American League in 1901. It was the third consecutive season in which they won the pennant but lost the World Series. Center fielder Ty Cobb won the Triple Crown and pitcher George Mullin led the league in wins (29) and winning percentage (.784).

The 1909 World Series was the championship series in Major League Baseball for the 1909 season. The sixth edition of the World Series, it featured the National League champion Pittsburgh Pirates against the American League champion Detroit Tigers. The Pirates won the Series in seven games to capture their first championship of the modern Major League Baseball era and the second championship in the club's history. This Series is best remembered for featuring two of the very best players of the time, Pittsburgh shortstop Honus Wagner, and Detroit outfielder Ty Cobb.