The club announced the deal on Twitter: "We have agreed to terms with @_BigBen7 on a new contract. More details to come on Steelers.com."
Terms of the deal were not disclosed. Roethlisberger, who tied the Saints' Drew Brees for an NFL-best 4,952 yards passing last season, was entering the final season of an eight-year, $102-million deal. The new contract keeps him with Pittsburgh through the 2019 season.
Roethlisberger threw for 32 touchdowns and had only nine passes intercepted in helping the Steelers win the AFC North Division with an 11-5 record. Pittsburgh lost to the Baltimore Ravens in the wild-card round of the playoffs.
The Steelers tweeted Roethlisberger's reaction, which he retweeted.
"I've always said this is where I want to be," Roethlisberger said. "It's home. It's family. As much as my wife and my kids are family, so is the Rooney family and my teammates and coaches."