"After a lot of thought and prayer, I've decided to accept the unknown and retire from my NFL career," Ware said in the Twitter post.
Ware came to the Broncos from the Dallas Cowboys as part of Denver's free-agency binge in 2014, when cornerback Aqib Talib, receiver Emmanuel Sanders and safety T.J. Ward were also signed. All four players were selected to at least one Pro Bowl since then.
Ware was saluted in tweets by John Elway, the Broncos and the Cowboys. Ware is Dallas' all-time sacks leader, with 117.
Cowboys owner Jerry Jones said Ware was everything he could have ever wanted in a player.
"He was one of the most dominant NFL players at his position in his era, and he was one of the most dynamic players in the history of the Dallas Cowboys. We wish nothing but the best for DeMarcus and his family, and we appreciate and respect his contributions to the NFL and to our team," Jones said in a statement.
Peyton Manning, who shared with Ware the leadership of the Broncos' team that won Super Bowl 50, congratulated his former teammate and co-captain.
"DeMarcus Ware is not only a Hall of Fame player, but a Hall of Fame teammate as well. I played against DeMarcus and played with him. It was an honor and a privilege to have done both. Being a teammate with DeMarcus and being a captain of the team was a real privilege for me," Manning said.
Linebacker Von Miller said a big part of his rebound from his 2013 suspension for violating the league's substance abuse policy to a perennial defensive player of the year candidate has "been because of DeMarcus. I have so many reasons to thank him."
Both Miller and Talib congratulated Ware on his announcement in separate Instagram posts.
Former Broncos coach Gary Kubiak said in a statement that it was a privilege for him to coach Ware and congratulated the linebacker on a "Hall of Fame career."
"DeMarcus was one of the great players in this league for many years and one of the finest human beings you'll ever come across. He was a once-in-a-generation player who will go down as one of the all-time great pass-rushers in NFL history. Just as important, he showed so much class and leadership with everything he did on and off the field," Kubiak said.
Ware has been a team captain in his time with the Broncos and universally respected in the locker room. He said in the days before Super Bowl LI that he planned to return from back surgery that sent him to injured reserve just before the regular-season finale.
Back troubles have been a part of his career, but especially the past two seasons with the Broncos. His 2016 season was especially difficult, as he missed most of the offseason work with an infection in his back that required repeated IV antibiotics to treat. He also missed five games with a fractured forearm last season.
A nine-time Pro Bowl selection, Ware will turn 35 in July and is eighth all time in sacks with 138½.
Ware needed one sack to tie newly minted Hall of Famer Jason Taylor, and with four sacks he would have passed Michael Strahan and moved into sixth place all time.
In nine seasons with the Cowboys, Ware earned Pro Bowl honors every year from 2006 to 2012. But he had a career-low six sacks in 2013 and missed the first three games with a quadriceps strain. Dallas released him after the 2013 season.
With the Cowboys, Ware had a streak of seven seasons with at least 11 sacks, recording 20 sacks in 2008 and 19½ sacks in 2011.
The Cowboys selected Ware in the first round of the 2005 draft with the 11th pick.
DeMarcus Ware calls it a career, announces his retirement from the NFL after 12 years
One of the best pass-rushers of his era has decided to call it quits on his NFL career. Former Dallas Cowboys and Denver Broncos star DeMarcus Ware announced his retirement on Monday.
Ware spent the first nine years of his career in Dallas before moving to Denver, where he finally became a Super Bowl champion. He retires with 138.5 sacks, eighth-most in NFL history and more than any other player since he entered the league in 2005. Just how prolific a sack artist was he? Well ...
It had been rumored in recent weeks that Ware, who turns 35 this summer, might actually return to the Cowboys, who desperately need pass-rush help. Instead, he‘ll hang up his spikes for good. Both of his former teams acknowledged his excellence on Twitter in the wake of the announcement.
One of his former teammates, cornerback Chris Harris, shared his admiration for Ware as well.