The 1940 Major League Baseball season was contested from April 16 through October 8, 1940. Both the American League (AL) and National League (NL) had eight teams, with each team playing a 154-game schedule. The Cincinnati Reds won the World Series over the Detroit Tigers in seven games. Hank Greenberg of the Tigers and Frank McCormick of the Reds won the Most Valuable Player Award in the AL and NL, respectively.

The 1940 World Series matched the Cincinnati Reds against the Detroit Tigers, with the Reds winning a closely contested seven-game series. The victory secured the Reds the second championship in their franchise history and came 21 years after their victory over the scandal-tainted Chicago White Sox in 1919. This would be the Reds' last World Series championship for 35 years despite appearances in 1961, 1970, and 1972. Meanwhile, Bill Klem worked the last of his record 18 World Series as an umpire.