In an Instagram post on his account focused on fatherhood and features pictures of his children, Harrison wrote: "I've missed way too much for way too long.and I'm done". "If anything, he's getting better".
This is the second time Harrison has called it quits.
The Patriots and Harrison had been in contact earlier this offseason about a possible return, but those talks never materialized into a new contract.
7 inmates dead and 17 injured after South Carolina prison fight
Lee County Fire & Rescue says multiple agencies were called into assist with the "mass-casualty incident" at the prison. South Carolina Department of Corrections did not immediately return a request for comment Monday morning.
"I maybe want to play a year at 40, maybe 41", Harrison said. Counting on him from Week 1 on is a much different matter.
Known for delivering hard hits, Harrison began his National Football League career with Pittsburgh in 2002 and helped the Steelers capture the Super Bowl in 2006 and again in 2009.
Be sure to do an extra bench press and set of leg squats for James Harrison on Monday. The five-time Pro Bowler and 2008 NFL Defensive Player of the Year announced on Instagram he is stepping away from the game following a 15-year career. Considering Harrison didn't become a regular starter for the Steelers until he turned 29, he made up for lost time in a big way.
In 2009, Harrison returned an interception 100 yards for a touchdown on the final play of the first half to give the Steelers a 17-7 lead on the way to a 27-23 triumph over Arizona.