The 1912 major league baseball season began on April 11, 1912. The regular season ended on October 6, with the New York Giants and Boston Red Sox as the regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the ninth modern World Series on October 8 and ended with Game 8 on October 16. The Red Sox defeated the Giants, four games to three (with one tie), capturing their second championship in franchise history, since their previous in . Going into the season, the defending World Series champions were the Philadelphia Athletics from the season.
This was the second 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.
During the season, Harper's Weekly conducted a detailed accounting of the expenses of major league clubs, reaching a figure of approximately $175,000 to $200,000.
The Boston Rustlers renamed as the Boston Braves.
The 1912 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 .
Opening Day, April 11, featured all sixteen teams, only the second time every team has started their season on the same day (first being two years prior with the season). The final day of the regular season was on October 6. The World Series took place between October 8 and October 16.
The 1912 season saw the following rule change:
An asterisk (*) denotes the ballpark a team played the minority of their home games at
13 tie games (8 in AL, 5 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 8 and ended on October 16 with the Boston Red Sox defeating the New York Giants in the 1912 World Series in seven games.
<section begin=Bracket/> <section end=Bracket/>
<sup>1</sup> National League Triple Crown batting winner
The 1912 season saw two teams play their last seasons at their respective venues.
The 1912 season saw three teams play in new venues.
League Park, the home of the St. Louis Cardinals, was renamed to Robison Field by Helene Britton, named after her father and uncle, Frank and Stanley Robison, respectively.
To accommodate for large crowds, the New York Highlanders would play three home games at the Brush Stadium, home of the New York Giants, on May 30 and a doubleheader on September 2.