An MRI this week revealed Darnold had an incomplete fracture of the scapula on his right (throwing) shoulder.
The injury is believed to have occurred in Sunday's 24-6 loss to the New England Patriots. There is one play in which Darnold took a forearm to the scapula area from linebacker Kyle Van Noy early in the second quarter that could be the source of the injury.
P.J. Walker, who played for Panthers head coach Matt Rhule at Temple and starred in the XFL before signing with Carolina last year, will get his second NFL start on Sunday when the Panthers (4-5) play at the Arizona Cardinals (8-1).
He won his first start last year 20-0 against the Detroit Lions.
The Panthers bolstered their quarterback depth Thursday, bringing back Cam Newton, who led the team to the Super Bowl in 2015, on a one-year contract.
The deal is worth up to $10 million for the remainder of the season, including $4.5 million guaranteed and a $1.5 million roster bonus, a source told ESPN's Adam Schefter.
The Panthers, who selected Newton with the first overall pick in the 2011 draft, released him following the 2019 season after he had struggled for several years with shoulder and foot injuries. They began a new regime with Rhule at that time.
Newton, the 2015 NFL MVP, started 15 games for the New England Patriots in 2020 before being released in training camp this year after the team decided to go with rookie Mac Jones as the starter.
Information from ESPN's David Newton was used in this report