But Gareth Bale - who broke David Beckham's record for most appearances for a British player in La Liga - opened the scoring against before Ronaldo doubled the lead.
Getafe saw forward Loic Remy sent off for a second caution early in the second half, but reduced the deficit in the 65th minute through a controversial penalty from Francisco Portillo only for Ronaldo to wrap things up with a late header.
After Real's five-game winning streak in all competitions was snapped by a surprise defeat at Espanyol on Tuesday, the coach said it was vital his side returned to winning ways ahead of their trip to Paris for the second leg of their last-16 tie.
Real's victory moved them four points clear of Valencia, who have a match in hand, and provided the flawless build-up to next week's crucial Champions League last-16 second leg against Paris Saint-Germain.
But Zidane, who has injury concerns of his own with Los Blancos, rejected the notion it will be a one-sided affair without the presence of the Brazilian superstar.
Barcelona beat nearest challengers Atletico Madrid 1-0 thanks to an outstanding free kick from Lionel Messi on Sunday to move eight points clear at the top of La Liga and closer to a 25th Spanish title.
There's a very important date for us and for the club.
"Players will always think about a big game, it's natural, but we have to think about tomorrow's game [against Getafe] more than anything".
After the match at the Santiago Bernabeu, Zidane told the press: "The game went just as we'd planned and we looked very good".
"I don't know, they haven't trained with us", he remarked. "I am also happy with how Theo played". "All the players looked focused, and it's great to go into Tuesday's game off the back of a win". "We're not thinking about an easy game", Zidane said.
"He's going to be in Paris and I'm very happy because he is going through a very good moment", Zidane, however, said.