Coach Kevin Willard revealed the news following the Pirates' 76-65 loss to No. 6 Syracuse on Saturday night at the Prudential Center.
"We hope it's only eight weeks," Willard said, regarding Mobley's recovery time from surgery. "Get him back by June, and he can have a full summer and rehab and get stronger and work on his game."
Mobley, a sophomore, is fourth on the team in scoring (9.0 points per game) and third in rebounding (5.5 per game). He has been playing through the shoulder injury, but dislocated it again while stretching earlier this week, according to Willard.
The only reason Mobley played against Syracuse, according to the coach, was because he had several family members in attendance.
Seton Hall (13-13, 2-11) has now lost seven games in a row for the first time since 2002, and is in second-to-last place in the Big East.
The Pirates have had to deal with several injuries this season. Forward Patrik Auda was lost after just five games with a broken bone in his foot. Swingman Brian Oliver also sat out the Syracuse game with what Willard called a "self-proclaimed" ankle injury. He is out indefinitely.
"It's one of those amazing injuries that when a game appears, it kind of goes away and feels really good, and when practice appears it really hurts," Willard said of Oliver's injury. "We do have the New England Journal of Medicine coming to study him, because they wanna know how that's possible. It's quite amazing."