Three-time World Player of the Year Ronaldo returned after a three-game absence due to a thigh injury as Real sealed their place in the final against local rivals Atletico Madrid on May 28 in Milan with a 1-0 win over Manchester City on Wednesday.
Real trail La Liga leaders Barcelona and Atletico Madrid by just a point with two games remaining.
Real edge past City to set up all-Madrid final
And with the in-form Gareth Bale missing for Sunday's visit of Valencia to the Santiago Bernabeu due to a knee injury, Zidane said he has no reason to rest Ronaldo.
"I think he is going to play. I think he is in perfect shape," Zidane said on Saturday.
"You are talking about preparing for the Champions League final, but the best way is to think about the games we have remaining.
"The first of those is important and he is going to play the two (league) games remaining."
Ronaldo hails Zidane as Real reach Champions League final
Zidane has overseen a remarkable turnaround in Real's fortunes in his four months in charge since replacing the sacked Rafael Benitez just to keep them in the fight for La Liga.
Real have strung 10 consecutive league wins together since suffering their only La Liga defeat under Zidane at home to Atletico in February and the Frenchman says he will continue to believe in their title chances until it is mathematically impossible.
"It is 10 straight victories and we have to keep going. Now we have two finals left in La Liga," added Zidane.
"The message to the players is as long as there are minutes remaining, we should believe until the end. I will believe until the last second of the last game."
Real will also be without goalkeeper Keylor Navas due to an achilles injury.
However, French striker Karim Benzema and Brazilian midfielder Casemiro are in contention to play after missing the victory over City.
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