Roethlisberger exited Sunday's loss to the Seattle Seahawks before halftime and then underwent an MRI that confirmed the need for surgery. The Steelers did not disclose details of the injury.
Roethlisberger's 5,129 passing yards led the NFL last season, which marked the second time he accomplished that feat in his career. The 37-year-old threw for 351 yards with no touchdowns and one interception this year.
Former third-round draft pick Mason Rudolph will become the starting QB for the Steelers. He went 12 of 19 for 112 yards to go along with two touchdowns and one pick in his NFL debut against Seattle.
Rudolph said Monday afternoon that he learned Roethlisberger was dealing with elbow pain after the season opener, according to The Athletic's Ed Bouchette.
Though Roethlisberger has dealt with numerous injuries during his career, he's never played in fewer than 12 games in a single season.
At 0-2, the Steelers are off to their worst start since 2013.