The 1981 Pittsburgh Pirates season was the 100th season of the Pittsburgh Pirates franchise; their 95th in the National League. The Pirates finished fourth in the National League East in the first half of the season with a record of 25–23 and sixth in the second half with a record of 21–33.
October 22, 1980 – Jesse Jefferson granted Free Agency.
October 22, 1980 – John Milner granted Free Agency.
October 29, 1980 – Traded a player to be named later and cash to the Seattle Mariners. Received Odell Jones. The Pittsburgh Pirates sent Larry Andersen to the Seattle Mariners to complete the trade.
December 9, 1980 – Traded Bert Blyleven and Manny Sanguillén to the Cleveland Indians. Received Gary Alexander, Victor Cruz, Bob Owchinko and Rafael Vasquez.
January 13, 1981 – Drafted John Kruk in the 3rd round of the 1981 amateur draft, but did not sign the player.
January 19, 1981 – Signed Larvell Blanks as a free agent.
January 20, 1981 – Signed Rusty Torres as a free agent.
January 23, 1981 – Signed John Milner as a free agent.
February 23, 1981 – Signed Luis Tiant as a free agent.
April 1, 1981 – Traded Mickey Mahler and Ed Ott to the California Angels. Received Jason Thompson.
April 5, 1981 – Purchased Jim Smith from the Baltimore Orioles.
April 6, 1981 – Traded Bob Owchinko to the Oakland Athletics. Received a player to be named later and cash. The Oakland Athletics sent Ernie Camacho to the Pittsburgh Pirates to complete the trade.
May 4, 1981 – Signed Willie Horton as a free agent.
June 8, 1981 – Drafted Ray Krawczyk in the 1st round of the 1981 amateur draft.
June 8, 1981 – Drafted Jim Winn in the 1st round of the 1981 amateur draft.
June 8, 1981 – Drafted Lee Tunnell in the 2nd round of the 1981 amateur draft.
June 8, 1981 – Drafted Bip Roberts in the 5th round of the 1981 amateur draft, but did not sign the player.
June 8, 1981 – Drafted Scott Bankhead in the 17th round of the 1981 amateur draft, but did not sign the player.
June 8, 1981 – Drafted Chris Bosio in the 29th round of the 1981 amateur draft, but did not sign the player.
June 8, 1981 – Drafted Lance Johnson in the 30th round of the 1981 amateur draft, but did not sign the player.
June 25, 1981 – Signed Denny González as an amateur free agent.
July 11, 1981 – Signed Bobby Bonilla as an amateur free agent.
August 20, 1981 – Traded John Milner to the Montreal Expos. Received Willie Montañez.
August 31, 1981 – Traded Phil Garner to the Houston Astros. Received players to be named later and Johnny Ray. The Houston Astros sent Randy Niemann and Kevin Houston to the Pittsburgh Pirates to complete the trade.
September 1, 1981 – Sold Grant Jackson to the Montreal Expos for $50,000.
