The Real Madrid coach revealed that the Portuguese forward will start in Friday’s Supercopa second leg against Atletico at Vicente Calderon after overcoming a muscle injury
Ronaldo had been a doubt for the clash after he was substituted due to a muscle strain at the Santiago Bernabeu on Tuesday.
However, Ancelotti confirmed the fitness of the Portuguese star after he trained with the squad on Thursday.
"Cristiano trained well with the group today," Ancelotti told a press conference.
"He has been training normally. He’s okay, he is available for tomorrow. He will be a starter."
After a 1-1 first-leg draw against Diego Simeone’s men, the 55-year-old says he is looking for more from his side in the away leg of the tie.
"I think we have to play with a little more intensity," he added. "The second part of the game we had offensive solutions, not the first, we were slow.
"The players are all well, but I'm going to change some positions in the field.
"We tend to play against Atletico a lot. I don't think it will change the style of play we've used before. They have the advantage of the result. They'll play with the same style as the first leg."
Ancelotti also declared he would stick with a 4-3-3 system despite the new roles of Toni Kroos and James Rodriguez in the side.
Ancelotti said: "The three midfielders will be normal. You may have to change it sometimes, for different characteristics. Kroos and James have played, for example, with different characteristics, but that does not change the scheme.
"I am happy with James. He is adapting to our game, he played well in his first two games."