Coach Matt Eberflus said Mooney is likely to undergo surgery.
Mooney leads the Bears with 40 catches and 493 receiving yards this season. He also led the team in those two categories last year and he's scored six times over the last two seasons.
Chase Claypool, Dante Pettis, Byron Pringle, Velus Jones, and Equanimeous St. Brown remain on hand at receiver in Chicago.
The injury is another setback for an offense that began to emerge as a potent threat behind the development of Fields as a dual-threat quarterback. Fields injured his non-throwing shoulder in Week 11 and missed Sunday's game against the Jets with the injury. His timetable to return is unclear.
There was no hope for a playoff run during Fields' breakout season. But the momentum of Chicago's ascending offense has been put on hold.