The following are the baseball events of the year 1891 throughout the world.

The American Association of Base Ball Clubs (AA) was a professional baseball league that existed for 10 seasons from 1882 to 1891. Together with the National League (NL), founded in 1876, the AA participated in an early version of the World Series seven times versus the champion of the NL in an interleague championship playoff tournament. At the end of its run, several AA franchises joined the NL. After 1891, the NL existed alone, with each season's champions being awarded the Temple Cup (1894–1897).