The deal is worth $99 million and can escalate to $108 million, according to a source. NFL.com was first to report the money.
"This is where I want to be," Roethlisberger said Friday afternoon with chairman Dan Rooney, team president Art Rooney II, coach Mike Tomlin and general manager Kevin Colbert among those watching his news conference. "It's an incredibly fair deal for both sides, and we're just excited to move forward and get some more Lombardi trophies in that room next year."
Roethlisberger has led the Steelers to their only two Super Bowl titles since the 1970s, and the 11-year veteran is coming off a Pro Bowl season in which he established career highs in passing yards (4,952), completions (408) and completion percentage (67.1).
He turned 33 on March 2, but Colbert said in January that the Steelers believe he is getting better and can continue to play at a high level into his late 30s, as Tom Brady and Peyton Manning have done.
"Ben has a number of great years ahead of him," Art Rooney II said.
Before Roethlisberger signed the new deal, he was heading into the final year of the eight-year, $102 million contract he signed in 2008, and the Steelers had remained steadfast that they would get a new deal done with their franchise quarterback.
He had a salary-cap hit of $18.395 million and was due a base salary of $11.6 million this year. Rooney declined to give specifics in regard to Roethlisberger's new deal and whether it lowered his cap hit for 2015.
The Steelers had been among the quietest teams during the first week of free agency, adding their first outside player Friday when they signed former Carolina Panthers running back DeAngelo Williams to a two-year contract.
Rooney said re-signing Roethlisberger to a long-term contract was the Steelers' top priority even after the start of the free-agent signing period Tuesday.
"For us, this was the most important," Rooney said.
Roethlisberger's wife Ashley, son Ben Jr. and daughter Baylee attended the news conference, and Roethlisberger said he wants to play his entire career with the Steelers so he can raise his children in Pittsburgh.
"People ask where I'm from," Roethlisberger said, "I'm from Pittsburgh."