Major League Baseball Commissioner Bud Selig will announce Thursday that he is officially retiring when his contract ends on Jan. 24, 2015, FOX Sports Insider Ken Rosenthal reports.

Selig has long insisted that he would step down when his current deal ends.

Selig has been in charge of MLB since 1992, first as an interim commissioner and then permanently in 1998.

By not staying on longer, Selig will fall short of surpassing Kenesaw Mountain Landis as the game's longest-serving commissioner.

This has been a busy season for the 79-year-old MLB boss.

He announced an extensive expansion of baseball's replay rules that is set to go into effect next season if approved by the owners, players union and umpires union.

He was also at the helm during MLB's most far-reaching crackdown on PED use, when the sport suspended 14 players as a result of the investigation into Biogenesis, the now-closed Florida anti-aging clinic accused of distributing banned performance-enhancing drugs.

New York Yankees 3B Alex Rodriguez received the stiffest penalty at 211 games and is the only one appealing.

Milwaukee Brewers outfielder Ryan Braun received a 65-game suspension while All-Stars Nelson Cruz, Jhonny Peralta and Everth Cabrera were among 12 banned on Aug. 5 for 50 games each.

Selig said at the time that he is proud of baseball's drug testing program. Since the program was first implemented in 2004, 32 major league players have been suspended for using banned substances. Three were suspended a second time.

In addition, 47 minor league players or players formerly in the major leagues have been suspended, including six repeat offenders.

"It took a long time,'' Selig said. ''I said we would aggressively enforce that program. Obviously if you have a tough testing program, you have to do that. Given the whole history and what we've accomplished: having the first testing program in baseball history -- baseball didn't have a drug testing program at any time in the '80s when, and I will say this very candidly, we had a very serious cocaine problem. There were the Pittsburgh drug trials, 29 players were convicted, four went to jail and the union still wouldn't agree to a program.

"So I'm proud of what we've done, we will continue to enforce the program."

Selig's family owned the Brewers from 1970 until 2005.

He has said he loves teaching and wants to write a book.

The Associated Press contributed to this report.