He said he will leave on Jan. 24, 2015, which would mark the second-longest term for a baseball commissioner behind Kenesaw Mountain Landis, who served from November 1920 to November 1944.
Selig bought the Seattle Pilots in bankruptcy court in 1970 and moved the team to Milwaukee. He became a leading owner by the early 1980s in his role as chairman of the Player Relations Committee, which determined labor policy.
He was part of the group that forced Fay Vincent's resignation and he took over as acting commissioner on Sept. 9, 1992, in his role as chairman of the executive council.
While he presided over a 7-month strike in 1994-95 that led to the cancellation of the World Series for the first time in 90 years, MLB and its players have had labor peace since.
Although he repeatedly said he would not take the job full time, he was formally elected commissioner July 9, 1998. He turned running the Brewers over to his daughter Wendy, but the Selig family did not sell the franchise until 2005.
Selig agreed to new contracts in 2001 and 2004. He first announced his planned retirement in 2003, telling a group from Associated Press Sports Editors he would leave when his current term expired at the end of 2006.
"For a guy who took it in Sept. 9, 1992, and I told my wife it was two-to-four months 14 years later ... I think that will be enough. There's no question, because there are other things I really would like to do."
Asked again if this was his final term, Selig responded; "Oh, there's no question."
He then agreed to new contracts in 2004, 2008 and 2012.
Selig was at the helm while baseball was criticized for being slow to react to the rise of performance-enhancing drugs. Management didn't have a drug agreement with its players from October 1985 until August 2002, and drug testing with penalties didn't start until 2004. Selig has repeatedly defended his record, saying baseball acted as fast as it could in a matter that was subject to bargaining with players.
Owners have repeatedly praised his financial stewardship, which has led to record franchise values as shown by the $2 billion sale of the Los Angeles Dodgers in 2012. MLB revenues, which totaled $1.7 billion in 1992, are projected to top $8 billion this year, and the average player salary has tripled under his tenure to more than $3 million.