February 22 – George Wright signs a contract to play for the Boston Red Caps after sitting out the 1880 season. Wright will only play part-time in order to devote more time to his sporting goods business.
April 11 – The Eastern Association is formed and includes the New York Metropolitans, The Washington Nationals and Brooklyn Atlantics, all teams that have regularly played competitively against National League teams.
April 27 – With pitcher George Bradley already out with pneumonia, the Detroit Wolverines lose their other hurler Bill Sweeney to a hemorrhage of the lungs. Neither pitcher will ever play a single game for the Wolverines.
May 14 – Charley Jones wins a judgement against the Boston Red Caps for his unpaid salary due from 1880 in an Ohio court. Cleveland law enforcement will take the money from the Red Caps share of gate receipts when Boston plays in Cleveland.
May 20 – Mike "King" Kelly scores the go-ahead run by cutting short the distance rounding the bases. Kelly doesn't come close to touching third while the umpire is looking a different direction. Kelly then pulls off the hidden ball trick in the 9th inning to preserve the win for the Chicago White Stockings.
May 28 – A man is arrested for trying to bribe John Clapp of the Cleveland Blues to throw a game. Clapp will acquire the nickname "Honest John" because he went to the police after the bribe offer was made.
June 1 – Tommy Bond is released by the Boston Red Caps after starting the season 0–3. After averaging nearly 500 innings pitched per season over the last 7 years, Bond's arm is no longer what it once was. Bond will never regain his once-dominating form.
June 18 – The Washington Nationals of the Eastern League disband, citing lack of interest after being rejected to join the National League.
September 3 – Lip Pike of the Worcester Ruby Legs makes 3 errors in the 9th inning which gives the Boston Red Caps 2 runs and a 3–2 victory. Worcester accuses Pike of throwing the game and immediately suspends him. Pike will only play in 1 more game in his career, in 1887.
September 15 – Davy Force of the Buffalo Bisons turns 2 unassisted double plays, participates in 2 other double plays and starts a triple play for the Bisons. Despite his feat, Buffalo loses in 12 innings, 7–6 to the Worcester Ruby Legs.
September 25 – The National League announces that all 8 teams will return for the 1882 season. This is the first time that the major leagues have had the same teams in 2 consecutive seasons.
September 27 – The Troy Trojans lose to the champion Chicago White Stockings 10–8 in a heavy rain storm in front of 12 spectators, setting a record for the least attended game.
September 29 – The National League issues a list of 10 blacklisted players who will require unanimous league approval for reinstatement. The reason given for the blacklisting is "confirmed dissipation and general insubordination."
November 3 – The American Association elects Denny McKnight as president. The new league will have no reserve clause and will allow Sunday games, liquor sales and 25¢ tickets, all in opposition to National League policies, in an effort to take the established major league head-on.