The 1918 Boston Red Sox season was the 18th season in the franchise's Major League Baseball history. The Red Sox finished first in the American League (AL) with a record of 75 wins and 51 losses, in a season cut short due to World War I. The team then faced the National League (NL) champion Chicago Cubs in the 1918 World Series, which the Red Sox won in six games to capture the franchise's fifth World Series. This would be the last World Series championship for the Red Sox until 2004.

The 1918 Chicago Cubs season was the 47th season of the Chicago Cubs franchise, the 43rd in the National League and the third at Wrigley Field. The Cubs finished first in the National League with a record of 84–45, 10.5 games ahead of the second place New York Giants. The team was defeated four games to two by the Boston Red Sox in the 1918 World Series.