Brown's announcement on Buffalo radio station WECK wasn't a surprise, but it brought his decorated career to an official end. He missed the entire 2008 season while trying in vain to latch on with a team.
"I came to the conclusion it's time to hang it up," Brown said. "I'm going to officially retire this week. I'm going to submit my paperwork to the NFL. ... I am terminating my active playing days.
"It's a wrap. There's no more football for me. They're always inquiring if I'm done. Yeah, that's it. There's no more. It was an awesome ride."
Brown last played in 2007 for the Chicago Bears, who declined to re-sign him after four seasons with them. He played only eight games that year because of a right shoulder injury.
He was a nine-time Pro Bowler, including eight straight trips to Honolulu from his second pro season until he left the Bills after 2003. His final Pro Bowl season was with the Bears in 2006, when he started every game in their Super Bowl run.
Brown will turn 37 on Feb. 13. He missed a combined 11 games in 2004 and 2005 with chest, knee and neck injuries.
Tim Graham covers the NFL for ESPN.com.