The 1975 World Series was the championship series of Major League Baseball's (MLB) 1975 season. The 72nd edition of the World Series, it was a best-of-seven playoff played between the American League (AL) champion Boston Red Sox and the National League (NL) champion Cincinnati Reds. The Reds won the series, four games to three. In 2003, ESPN ranked it the second-greatest World Series ever played, trailing only the 1991 series, while in 2020, Sam Miller of ESPN named it the best World Series ever.

The World Series is the annual final championship series of Major League Baseball (MLB) in the United States and Canada. It has traditionally been held in October, though some more recent editions were contested in November due to expanded playoffs and/or season delays. It has been contested since 1903 between the champion teams of the American League (AL) and the National League (NL). The winner of the World Series championship is determined through a best-of-seven playoff, and the winning team is awarded the Commissioner's Trophy.