He has been ruled out for Sunday's game at the Los Angeles Lakers and will be re-evaluated this week to determine when he can return to play.
Westbrook suffered the injury with 2.5 seconds remaining in the fourth quarter against the Portland Trail Blazers on Friday when teammate Andre Roberson inadvertently kneed him in the face, leaving a visible dent in the side of his face.
Westbrook left the game without speaking to reporters in order to carry out further evaluation at a local medical facility.
The zygomatic arch bone separates the eye socket from the sinuses.
Westbrook had his third consecutive triple-double against the Blazers, scoring 40 points with 13 rebounds and 11 assists. He had a historic February, averaging 31.2 points, 9.1 rebounds and 10.3 assists, numbers that only ever have been totaled by Hall of Famer Oscar Robertson.
Kevin Durant is set to be re-evaluated for a minor procedure he underwent last Sunday and could return as soon as this week. In seven games without Durant in February, Westbrook averaged a triple-double -- 31.2 points, 10.0 rebounds and 11.3 assists.
Westbrook, 26, is averaging 26.5 points, 6.8 rebounds and 8.1 assists in 45 games this season. He missed 14 games in November because of a fracture in his right hand.
Newly acquired D.J. Augustin will start in place of Westbrook on Sunday against the Lakers.
Westbrook Undergoes Surgery On Cheekbone
Royce Young breaks down how Russell Westbrook's facial injury, which will keep him out of the Thunder's game against the Lakers, will impact Oklahoma City's playoff chances.
How Serious Is Westbrook's Injury?
Dr. Mark Adickes evaluates the severity of Russell Westbrook's facial injury.
Roberson Accidentally Collides With Westbrook
Oklahoma City Thunder guard Andre Roberson mistakenly collided his knee with guard Russell Westbrook's head after tripping over him.
Blazers Fend Off Westbrook, Thunder
Highlight Of The Night: Despite Russell Westbrook's triple-double of 40 points, 13 rebounds and 11 assists, the Thunder couldn't put away the Blazers and fell 115-112.