Brewer tweeted on Friday that he will be ready for the season opener, Nov. 1 against the Nets in Brooklyn.
"If y'all haven't already heard I had successful meniscus surgery. Started rehab this morning. Minor setback for a major comeback," he tweeted. "I appreciate the prayers and get well soons from everyone. Much appreciated. Will for sure be 100 (percent) for season opener."
The team said Brewer had suffered a medial meniscus tear in the past two weeks.
Brewer's agent, Henry Thomas, said the injury wasn't from a specific incident but rather from "wear and tear over time."
The Knicks' orthopedic surgeon, Dr. Answorth Allen, performed the procedure.
Shooting guard Iman Shumpert is still recovering from a torn left ACL suffered during the playoffs. With Brewer injured, the Knicks could turn to J.R. Smith to be their initial starter while Brewer gets into a rhythm. That also means that James White, who signed in the offseason, could see an increased role at the start of the season.
Injuries were a problem for the Knicks in 2011-12. Carmelo Anthony, Amare Stoudemire, Jeremy Lin, Baron Davis and Jared Jeffries all suffered moderate to significant setbacks. Davis, Shumpert and Stoudemire were all sidelined at some point during the team's first-round exit from the playoffs, while Lin missed it entirely.
Jared Zwerling is a regular contributor to ESPNNewYork.com.