PITTSBURGH -- The last Killer B left will guide the Steelers into a new era.

The Steelers are giving quarterback Ben Roethlisberger a new two-year extension to go along with the one year he had left on his contract, tying him to Pittsburgh through the 2021 season, a source told ESPN's Adam Schefter.

Pittsburgh announced the signing Wednesday.

The extension all but guarantees Big Ben ends his career with the same franchise that drafted him in 2004.

"I am grateful to the Rooneys and the Steelers organization for continuing to believe in me," Roethlisberger said in a statement announcing the deal. "It has always been a goal to play my entire career in Pittsburgh. This is home for me and my family, and we love this city. I am as excited to be a Steeler in year 16 as I was when they drafted me. They will get my absolute best."

Roethlisberger, who turned 37 on March 2, had one year left on a four-year, $87.6 million extension he signed in 2015. That deal included a $12 million base salary for 2019, which the Steelers have reworked as part of the new extension. Roethlisberger also earned a $5 million roster bonus on March 15.

With Le'Veon Bell leaving in free agency after a yearlong holdout and Antonio Brown forcing a trade to the Oakland Raiders, Roethlisberger is essential in guiding Pittsburgh past a drama-filled offseason.

The Steelers began discussing a new deal for Roethlisberger after the 2018 season, but the sides hadn't agreed to terms in time for the new league year. Complicating matters is a ballooning quarterback market: Seattle Seahawks star Russell Wilson became the highest-paid player in the NFL when he signed a four-year, $140 million contract extension last week.

Since the Steelers typically don't guarantee their contracts beyond the signing bonus, Roethlisberger's deal is likely to include multiple roster bonuses.

Roethlisberger has two Super Bowl victories and ranks sixth all time in passing yards (56,194) and seventh in touchdowns (363). He led the NFL in passing yards in 2018 with 5,129. The Steelers never have had a losing season with him at quarterback, and he is among the franchise leaders in career games played, with 216.

The quarterback has been the subject of public criticism for his dealings with Brown, who had six straight 100-catch seasons before leaving Pittsburgh. Brown wasn't happy when Roethlisberger criticized the receiver's route running on a radio show after a Week 12 loss to the Denver Broncos. Brown later tweeted that Roethlisberger has an "owner mentality" by calling out coaches and teammates who are afraid to question him.

Brown later told ESPN's Jeff Darlington in an on-camera interview that he got mixed messages from his quarterback.

"If I'm your guy, make me know I'm your guy, but don't say I'm your guy and point fingers," Brown said. "Don't say I'm your guy and then don't throw me the ball the whole first quarter."

General manager Kevin Colbert defended Roethlisberger during a media session in mid-February but created more heat when he said the QB had "52 kids" under him. Colbert later specified on NFL Network that he was trying to convey that Roethlisberger has more experience than his teammates, along with a Super Bowl pedigree.

"Ben is the unquestioned leader of this group," Colbert said Feb. 20. "He's the elder statesmen and the [only] Super Bowl winner [remaining on the roster]. If our players were smart, they'd listen to him because he's been there, he's done it. He can tell them, 'No, guys, what you're doing is or is not good enough.' And I honestly believe that can be a burden on him more often than he may like to admit, because he has to ... he's got 52 kids under him, quite honestly. I want them to step up and say, 'Hey, Ben, what do I have to do? Can I do this better? What do we have to do to win a Super Bowl?'

"I think that once you win it, you've got 53 guys who can say what it took, but right now, he's the only one, so I have no problem with him. He can call me out, and that's fine."

In 2019, Roethlisberger will be tasked with leading an increasingly young locker room and lifting a passing game that lost two major talents in as many years. The team is giving him multiple years to do just that.