The former England Under-21 international sustained the injury during pre-season and he has already missed the Canaries opening two matches of the new season.
Norwich boss Daniel Farke has now confirmed that the prognosis is not good for the 24-year-old, as he is set to go under the knife and is unlikely to return to the first-team fold until mid-November.
"It's bad news for Alex Pritchard," Farke told Norwich's official website. "He needs an operation so we will have to do without him for at least 12 weeks.
"He's a key player for us but sometimes in football there are injuries. We have to handle it, and we will."
Pritchard's absence will certainly be a blow for Norwich as he featured regularly last season following his switch from Tottenham, scoring six goals in 30 Championship appearances.
Norwich are next in action when they play host to Sunderland at Carrow Road on Sunday.