The Ballon d'Or winner has lauded the Frenchman for bringing a sense of "calm" to the Bernabeu last term, while he has set out his goals for this term
Zidane, 44, replaced Rafael Benitez at the start of January, leading Madrid to European glory thanks to a penalty shoot-out victory over city rivals Atletico in the final.
Ronaldo, who scored 51 goals in all competitions last season, paid tribute to the Frenchman as the reason his team's campaign turned around.
"Zidane was the key to our season," he said.
"He came, made us work hard, work well. He's a great professional and a great person.
"In my opinion, his best quality is his ability to give players a sense of calm. What coach can win the Champions League in six months?
"Zidane deserves much credit and I am very happy he is with us."
After leading Portugal to Euro 2016 glory, Ronaldo has been sidelined with a knee injury, although he is nearing a return.
The 31-year-old said his aims for this season were similar to any other at the Santiago Bernabeu – to win trophies.
"Playing for the best club in the world, Real Madrid, the goal is always to win titles," Ronaldo said.
"Obviously, the Champions League is the trophy that means more for Real Madrid, who have won it more than anyone else and it is always a major competition.
"It is special for me and for Madrid, so we will try to win it again this year."