Urlacher tweeted: "It was an honor to play my entire career for the @ChicagoBears"
In a separate tweet, posted about the same time, the Bears' official Twitter feed announced, "Former #Bears star Brian Urlacher has announced his retirement from the NFL."
Urlacher's tweet linked to a longer statement:
''After spending a lot of time this spring thinking about my NFL future, I have made a decision to retire. Although I could continue playing, I'm not sure I would bring a level of performance or passion that's up to my standards. When considering this, along with the fact that I could retire after a 13 year career wearing only one jersey for such a storied franchise, my decision became pretty clear. I want to thank all of the people in my life that have helped me along the way. I will miss my teammates, my coaches and the great Bears fans. I'm proud to say that I gave all of you everything I had every time I took the field. I will miss this great game, but I leave it with no regrets."
Urlacher, an All-American at the University of New Mexico, was drafted by the Bears with the 9th overall pick in the 2000 NFL Draft. He was selected to eight Pro Bowls as a middle linebacker.