Alaves went close to breaking the deadlock on 31 minutes when Alfonso Pedrazaplayed a neat one-two with Manu Garcia before firing just over the bar from 18-yards out.
Ronaldo took his 2018 goal tally to 12 with a brace either side of a cool finish from Bale, whose long-term future at Madrid has been the subject of speculation this week.
Benzema then scored his fourth goal of the season in the 89th minute, firing home from the penalty spot after Victor Laguardia had brought down Bale. After the game, Zindane hailed Ronaldo's kind gesture, telling ESPN: "I am happy for Cristiano's nice gesture with Karim".
"This shows he is a team player".
Despite missing his own chances to put himself on the scoresheet in the first half, he first set up Cristiano Ronaldo in the 44th minute of the game with an excellent back-heel, before assisting Gareth Bale in the 46th minute to help double Los Blancos' lead. It is something positive for me.
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Prior to the penalty goal, Benzema had only scored three goals, and Ronaldo's act does not surprise Navas.
"I'm proud of everything we're doing at the moment, we are showing character and personality, and scoring 26 goals in the last six games is lovely", Zidane told a news conference on Friday.
He added: "They played a very good game today - also Lucas Vazquez, the four up front all played very well".
The visitors produced a rather tepid display after the interval and fell further behind when Bale picked out Vazquez down the right and his cross was swept in by Ronaldo just after the hour mark. "Maybe we needed a game like this". Though he has endured a hard time in the Spanish capital in terms of fitness issues, he has proved to be a key player in his side at vital moments, netting in the 2014 European Cup final to win La Decima as well as the Copa del Rey final against Barcelona that same year.
Real Madrid travel to face Espanyol in La Liga on Tuesday night, live on Sky Sports Football, with Alaves turning their attentions to hosting Levante on Thursday evening.