Los Blancos returned to duty having scored just once in their previous three LaLiga matches, but France international Varane netted either side of half-time to put them firmly in control against Jose Bordalas' men.
Luka Modric added a third deep into additional time to wrap up Madrid's biggest league win since November 9, and Zidane said his side's patience had paid off in the derby fixture.
🎙💬 "This is always a difficult place to come and we fought to win the three points."— Real Madrid C.F. 🇬🇧🇺🇸 (@realmadriden) January 4, 2020
Goalscorer @raphaelvarane spoke to #RMTV after this afternoon's victory at @GetafeCF! #RMLiga pic.twitter.com/O5bvpMK4Gp
"I already said that you have to be calm in front of goal," the Madrid coach told reporters.
"You have to be calm because sometimes the ball does not fit. And with goals today from Varane, it shows that we have many resources to score.
"For us, it is important to win here because it is a very complicated league. The boys have been plugged in since minute one with great intensity."
Zidane also paid tribute to goalkeeper Thibaut Courtois, who kept his third consecutive clean sheet to help his side go top of the table, albeit with previous leaders Barcelona playing later on Saturday.
The Belgium international was unbeatable in goalless draws with Barca and Athletic Bilbao prior to the mid-season break, leading to Zidane underlining the importance of his performances.
"I am happy for him and sure he is happy with his work," Zidane said of Courtois. "We are happy for him and he is for us.
"We have suffered in some games and Courtois has been very good. We have played as a team, which is the most important in these games and against these teams.
"We achieved a good result as a team, thanks to everyone’s efforts."