Urlacher recorded a franchise-record 1,779 tackles, 41 1/2 sacks, 22 interceptions, 16 fumble recoveries and 11 forced fumbles.
He was named NFL Rookie of the Year in 2000, and twice won the Brian Piccolo Award.
It will be interesting to see if both Lewis and Urlacher are first-ballot Hall of Fame selections in five years when they're eligible for enshrinement.
"After spending a lot of time this spring thinking about my NFL future, I have made a decision to retire," Urlacher said in a statement. "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 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."