It was another impressive attacking display as the in-form Hatem Ben Arfa led the way for Claude Puel's side, who have now won four successive league games and scored more goals than any other team this season.
A strong start from the visitors proved to be key as they claimed the lead in just the 14th minute when Wallyson found Mathieu Bodmer, who kept his composure in the box to slot the ball past Abdoulaye Diallo with the outside of his boot.
It proved to be a rare moment of concern for the visiting defence as Nice dominated and the lively Ben Arfa almost doubled the lead before the break when his low strike was tipped wide by Diallo.
The former Newcastle United attacker did register his side's second of the night early in the second half, and he did so in spectacular fashion as he led a break before beating two defenders to fire home an emphatic finish.
Much like the opening 45 minutes, Rennes continued to struggle to put Nice under pressure for an extended period, but they did come close when Kamil Grosicki shot wide from the edge of the box.
It was left to a couple of substitutes to secure the win, with Mahamane Traore drilling the ball in from close range after a cross had been deflected into his path.
Said Benrahma needed less than four minutes to make an impact as he made it 17 goals in the last four games from Nice by picking out the top corner with an unstoppable strike after collecting a short corner from Ben Arfa.
Rennes scored a late consolation when Grosicki slotted past Cardinale following good work from Juan Quintero, but it could not take the shine off another emphatic triumph for Nice.