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 1975 Boston Red Sox season was the 75th season in the franchise's Major League Baseball history. The Red Sox finished first in the American League East with a record of 95 wins and 65 losses. Following a sweep of the Oakland Athletics in the ALCS, the Red Sox lost the World Series to the Cincinnati Reds in seven games.