The 1903 Chicago Cubs season was the 32nd season of the Chicago Cubs franchise, the 28th in the National League, and the 11th at West Side Park. The Cubs finished third in the National League with a record of 82–56.

The 1903 major league baseball season began on April 16, 1903. The regular season ended September 29, with the Pittsburgh Pirates and the Boston Americans as regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the first modern World Series on October 1 and ended with Game 8 on October 13. The Americans defeated the Pirates, five games to three.