| 1931 MLB season | |
|---|---|
| League | American League (AL) National League (NL) |
| Sport | Baseball |
| Duration | Regular season:
|
| Number of games | 154 |
| Number of teams | 16 (8 per league) |
| Regular season | |
| Season MVP | AL: Lefty Grove (PHA) NL: Frankie Frisch (SLC) |
| AL champions | Philadelphia Athletics |
| AL runners-up | New York Yankees |
| NL champions | St. Louis Cardinals |
| NL runners-up | New York Giants |
| World Series | |
| Champions | St. Louis Cardinals |
| Runners-up | Philadelphia Athletics |
The 1931 major league baseball season began on April 14, 1931. The regular season ended on September 27, with the St. Louis Cardinals and Philadelphia Athletics as the regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the 28th World Series on October 1 and ended with Game 7 on October 10. In a rematch of the prior year's postseason, the Cardinals defeated the Athletics, four games to three.
This was the first season that the Baseball Writers' Association of America (BBWAA) selected a Most Valuable Player in each league.