"Robert Lewandowski has strained a ligament in his right knee. The FC Bayern striker will be out for around four weeks," a brief statement on the club's official website read.
Lewandowski was injured in Poland's World Cup qualifying win over Andorra on Sunday, ruling him out of their match against England on Wednesday, and had scans on Monday.
The Poland international will now miss the upcoming match against second-place RB Leipzig, who trail leaders Bayern by four points. He will also not take part in the two legs of the Champions League quarterfinals against Paris Saint-Germain in early April.
On course to break Gerd Muller's Bundesliga record of 40 goals in one season, Lewandowski has been in breathtaking form this season.
He has struck 35 goals in his 25 appearances this term and added five more in the Champions League plus two at the Club World Cup earlier this year.
With the Bundesliga pausing for the league cup semifinals without Bayern over the first weekend of May, the earliest projected return date would be the match against Borussia Monchengladbach on May 8.
Lewandowski would then have three matches to score six goals and secure himself the record.
Information from Reuters was used in this report.