The Borussia Dortmund winger says a scan has revealed a serious knee injury following his side's 2-2 draw against Augsburg on Saturday.
The Poland captain went down after a heavy challenge in the second minute and was replaced by Pierre-Emerick Aubameyang after lengthy treatment.
After a scan Sunday, Blaszczykowski took to his Facebook account to confirm that he will now be sidelined for the remainder of the season.
Next to a picture of his leg being supported by a doctor, the Poland international wrote: "Unfortunately, the assumption has been confirmed: it is a cruciate ligament injury. On Thursday I will have surgery and then the struggle for my comeback begins!"
Augsburg twice came from behind to secure a 2-2 draw at the Signal Iduna Park on Saturday as Dortmund's injury-hit campaign hit another stumbling block.
Coach Jurgen Klopp said his side "have only had bad news" so far this season, with a host of first-team players - including Mats Hummels, Neven Subotic, Sebastian Kehl, Ilkay Gundogan, Marcel Schmelzer and Lukas Piszczek - all having endured lengthy injury problems.
Dortmund has lost further ground on leader Bayern Munich, with the champions' 2-0 win over Borussia Monchendgladbach ensuring they finish the weekend 14 points ahead of last seasons' runners-up.