Swans manager Michael Laudrup revealed earlier this month that the Holland international needed to have an operation and that he expected the 30-year-old to be out for four to five weeks following the procedure.
The Dane had hoped Vorm would be able to last out until January but it has now been decided he will have an operation on Thursday, with Gerhard Tremmel poised to take over in goal again over the festive period.
A statement on the club's official website said: "Michel Vorm is set to go under the surgeon's knife today (Thursday) to rectify a long-standing knee problem.
"The Swans had hoped the Dutch keeper would battle through until January, but after suffering more problems against Norwich City last Sunday, it was decided that the injury could not be managed any longer.
"Surgeons will explore the knee before carrying out work on clearing any loose ligaments and fragments of bone, and a diagnosis on the length of time he will be sidelined depends on the scale of the operation."
Better injury news for Swansea is that midfielder Leon Britton and defender Chico Flores should be available to face Everton at the Liberty Stadium on Sunday.
Britton was back in training on Wednesday following a broken toe which has seen him miss the last five games.
Flores, who has now served a one-match ban, was also back on the training ground this week following a knee complaint.