The Panthers believe the injury happened in the second quarter of the team's 24-6 loss to the New England Patriots on Sunday. Darnold threw three interceptions in the loss, including one returned 88 yards by J.C. Jackson for a touchdown, when he missed tight end Ian Thomas, who was wide open.
Panthers coach Matt Rhule said Monday that Darnold reported soreness in his shoulder after the game and was sent for an MRI.
Darnold, acquired by the Panthers in an offseason trade with the New York Jets, has thrown 10 interceptions in the past six games, five of them losses. He is tied with Joe Burrow for the NFL lead with 11 interceptions this season.
In nine games this season, Darnold has thrown for 1,986 yards with seven touchdowns while completing 59.5% of his pass attempts. He also has five rushing touchdowns.
The Panthers are 4-5 after starting the season 3-0.
The news of Darnold's injury was first reported by NFL Network.
ESPN's David Newton contributed to this report.