San Mateo County Assistant District Attorney Karen Guidotti said Thursday that McDonald's attorney entered the plea on the player's behalf on Monday.
Guidotti says a pretrial conference has been set for Sept. 28 and a jury trial for Oct. 18, if he does not resolve the case.
McDonald was arrested June 12 after a California Highway Patrol officer pulled him over in his black BMW on Interstate 280 for allegedly driving 94 mph. His blood-alcohol content was not released.
McDonald publicly apologized after he was booked into a Redwood City jail.
If convicted, the 25-year-old could face a maximum of six months in jail.