Cleveland's star point guard, who only recently returned after missing 11 games with a broken finger, fractured a bone in his jaw when he took a hard fall in Friday night's loss at Milwaukee.
Irving did not travel with the Cavs to New York so he could be fitted with a protective mask that he will wear in Saturday's game against the Knicks at Madison Square Garden.
Irving was injured when he was knocked down in the first quarter by Bucks forward forward Luc Mbah a Moute, who was called for a foul. Irving's face slammed into the floor, and he writhed in pain for several minutes before getting up and making two free throws. He stayed in the game.
At the end of the quarter, last season's NBA rookie of the year sat on the bench with a towel on his face, but he played 36 minutes and finished with a team-high 26 points. Following the game, the Cavs indicated Irving would be on the flight to New York, but a CT scan at the Cleveland Clinic revealed what the team described as "a small left maxillary fracture."
Cavs forwards Tristan Thompson and Tyler Zeller are already wearing plastic protective masks for facial injuries sustained earlier this season.
This is the latest injury for Irving, who broke his hand this summer when he slapped a padded wall in frustration during a practice in Las Vegas. The 20-year-old's college career at Duke was limited to 11 games because of a severe foot injury.
Irving missed 15 games last season with a concussion and shoulder injury.
Friday's game was Irving's third since returning from the broken left index finger. He was expected to miss four weeks, but returned in three for the Cavs, who went just 2-9 without him.