The following are the baseball events of the year 1921 throughout the world.
Negro leagues final standings
Negro National League final standings
This was the second overall season of the first Negro National League. Chicago repeated as pennant champion.
East (independent teams) final standings
A loose confederation of teams were gathered in the East to compete with the West, however East teams did not organize a formal league as the West did.
Chicago, the best team of the "West" and Hilldale, the best team of the "East Coast", engaged in a "postseason series" that was played over eleven days in three states (Pennsylvania, Delaware, New Jersey). It was the first postseason series between two Negro league teams in eight years and it would be the first of six held in the 1920s. Hilldale won three games to Chicago winning two while Game 4 ended in tie. 
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. (June 2011)
- March 21 – Tom Vickery
- March 24 – Larry McLean
- March 25 – Harry Arndt
- March 30 – Frank Bancroft, 74, manager who won 1884 championship with Providence Grays, also managed six other teams; introduced baseball to Cuba in 1879, and was Reds executive for 30 years.
- March 31 – John Fitzgerald, 50, pitcher for the 1891 Boston Reds.
- April 3 – Pop Corkhill
- April 3- George Bechtel, Pitcher for the Louisville Grays one of the inaugural franchises in the National League.
- April 9 – Kid Butler
- April 21 – Tom O'Brien, 60, utility who played in each position except shortstop, while batting a .231 average for five different teams between 1882 and 1890.
- April 27 – Hal Mauck
- September 3 – Jim Clinton, 71, outfielder for 10 seasons; 1872–1876, 1882–1886.
- October 2 – Ed Carfrey
- October 20 – Jack Hardy
- October 24 – Jimmy Barrett
- October 27 – Bill Kuehne, 63, German third baseman for the Columbus Buckeyes, Pittsburgh Alleghenys & Burghers, Columbus Solons, Louisville Colonels, St. Louis Browns, and Cincinnati Reds during the 19th century.
- November 4 – Levi Meyerle, 76, infielder who won National Association batting titles in 1871 and 1874, later playing in the first major league game.
- December 9 – Charlie Morton, 67, player, manager, and later a minor league president.
- December 15 – Joe Weber
- December 22 – Socks Seybold