The team said Saturday that Westbrook would begin rehab immediately and that a timetable for his return to the court will be determined in the offseason. The surgery was performed at the Stedman Clinic in Vail, Colo.
"Although we are of course disappointed that Russell will be unable to return to the floor with his teammates this season, the opportunity to repair the meniscus as opposed to remove it was the best possible scenario for Russell's long term health as a player and person," Thunder executive vice president and general manager Sam Presti said in a statement. "Russell's health and well being are obviously our number one priority through this process and today's procedure helped solidify our belief that Russell will have many productive years of basketball in his future."
Westbrook was hurt when rookie Patrick Beverley tried for a steal in the second quarter of Game 2 and ran into his knee.
Coach Scott Brooks said Saturday at the team's shootaround that Reggie Jackson would start for Westbrook later in the evening in Game 3 of the best-of-seven series, which the Thunder lead 2-0.
It will be the first time Westbrook has missed a game in his career. He has appeared in an NBA-best 394 consecutive regular-season games and each of Oklahoma City's 45 playoff games.
"It sucks," James said. "He's a guy who's never missed a game his whole life. We're not just talking about the NBA. He's never missed a game in high school, college or Little League. It's unfortunate, especially for a great player like him, seeing how hard he works, especially being with the Olympic team. It's unfortunate. Hopefully, he has a speedy recovery."
Information from ESPN.com's Michael Wallace and The Associated Press was used in this report.