The 1948 major league baseball season began on April 19, 1948. The regular season ended on October 4, with the Boston Braves and Cleveland Indians as the regular season champions of the National League and American League, respectively. The Indians won the American League title via a tie-breaker game victory over the Boston Red Sox, after both teams finished their 154-game schedules with identical 96–58 records. This was the second regular season tie-breaker, and saw a change from the previous three-game format to that of a single-game, Game 163. The postseason began with Game 1 of the 45th World Series on October 6 and ended with Game 6 on October 11. The Indians defeated the Braves, four games to two.
The 1948 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 since the 1904 season (except for 1919) and would be used until 1961 in the American League and 1962 in the National League.
Opening Day took place on April 19, featuring six teams. The final day of the scheduled regular season was on October 3, which saw all sixteen teams play, continuing the trend from the 1946. Due to the Boston Red Sox and Cleveland Indians finishing with the same record of 96–58, a tie-breaker was scheduled, to be considered an extension of the regular season. The Indians won the Game 163 tie-breaker on October 4. The World Series took place between October 6 to October 11.