The Portugal international netted in the 5-3 win over Real Betis on Sunday evening to make it 10 in his last six outings, while also chipping in with a couple of assists in that time.
Ronaldo faced plenty of criticism in the first half of the season for a perceived failure to reach his form of past campaigns at the Bernabeu, but Zidane believes that the five-time Ballon d'Or winner is now showing signs of his best.
"He's looking good and we're thrilled to see him scoring and chasing things down up top," he told reporters after the win at the Benito Villamarin.
"We're heading into the business end of the season and every game is vital. To see all the players looking so sharp is fantastic and I'm very pleased."
Ronaldo has a combined 23 goals in 26 Champions League and La Liga appearances for Madrid this season.