The Portuguese attacker got the card for diving in the penalty area against Rayo Vallecano on Wednesday. TV images later showed that he had been tripped by a defender.
Real confirmed in a statement that the Spanish federation’s competitions committee had “cancelled the referee’s yellow card”.
Ronaldo avoids a one match suspension for his fifth yellow card meaning he will be available to play in a key match on Saturday against Eibar.
Real are second in the Spanish title race, four points behind leaders Barcelona. Coach Carlo Ancelotti will already be without James Rodriguez and Toni Kross, who are suspended. Gareth Bale is uncertain because of injury.