The 1913 major league baseball season began on April 9, 1913. The regular season ended on October 5, with the New York Giants and Philadelphia Athletics as the regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the tenth World Series on October 7 and ended with Game 5 on October 11. In the third iteration of this World Series matchup, the Athletics defeated the Giants, four games to one, capturing their third championship in franchise history, since their previous in . Going into the season, the defending World Series champions were the Boston Red Sox from the season.
This was the third of four seasons that the Chalmers Award, a precursor to the Major League Baseball Most Valuable Player Award (introduced in 1931), was given to a player in each league.
The Brooklyn Trolley Dodgers shortened its name to the Brooklyn Dodgers and the New York Highlanders renamed as the New York Yankees.
The 1913 schedule consisted of 154 games for all teams in the American League and National League, each of which had eight teams. Each team was scheduled to play 22 games against the other seven teams of their respective league. This continued the format put in place for the season. This format would last until .
National League Opening Day took place on April 9 with a game between the Philadelphia Phillies and Brooklyn Dodgers, while American League Opening Day took place the following day, with all AL teams but the Chicago White Sox and Cleveland Naps, playing. The final day of the regular season was on October 5. The World Series took place between October 7 and October 11.
The National League ruled that umpires could no longer scout for teams, as was the case when Umpire Cy Rigler was being paid $2,200 () by the Philadelphia Phillies for his role in having the team sign a pitcher, Eppa Rixey.
An asterisk (*) denotes the ballpark a team played the minority of their home games at
21 tie games (5 in AL, 16 in NL), which are not factored into winning percentage or games behind (and were often replayed again) occurred throughout the season.
The postseason began on October 7 and ended on October 11 with the Philadelphia Athletics defeating the New York Giants in the 1913 World Series in five games.
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<sup>1</sup> American League Triple Crown pitching winner
The 1913 season saw two teams move to two venues.
The Chicago White Sox renamed White Sox Park to Comiskey Park, named after team owner Charles Comiskey.
The Boston Braves play two doubleheaders on April 19 and May 30 at the home of the Boston Red Sox at Fenway Park to accommodate large crowds.