Griffin made his announcement Saturday night after UFC 160.
Griffin has fought just three times since November 2009 while struggling with multiple injuries. He beat Tito Ortiz in what turned out to be both veterans' final fight at UFC 148 last July.
UFC President Dana White says Griffin will work for the promotion.
Griffin gained fame on the first season of "The Ultimate Fighter," the UFC's reality show. He finished with a spectacular victory over Stephan Bonnar in April 2005 in a fight widely considered the most important in UFC history.
After Griffin won the UFC light heavyweight title in July 2008 with a victory over Rampage Jackson, he lost it to Rashad Evans five months later.