The British fast man has dominated the bunch sprints in this year's Tour and made no mistake to edge Alexander Kristoff of Norway and green jersey holder Peter Sagan.
After Thursday's dramatic finish on the Mont Ventoux and yesterday's individual time trial, this was a day for race leader Chris Froome to sit quietly in the peloton and avoid crashes.
He duly completed that task to remain one minute 47 seconds ahead of Dutchman Bauke Mollema, with fellow Briton Adam Yates in third overall.
Sunday will see the overall contenders severely tested over 160km from Bourg-en-Bresse to Culoz with two ascents of the Grand Colombier -- a feared mountain pass in the Jura Massif.
Cavendish is likely to have no more stage win opportunities until the race finale in Paris next Sunday on the Champs Elysees and took his latest chance in ruthless style.
Coming off the wheel of German rival Marcel Kittel, once the Manxman hit the front the result was never in real doubt.
Kittel threw up his arms in disgust as Cavendish cut in front of him, but his protests were in vain, well beaten again with fellow German Andre Greipel finishing just behind him in sixth.
"I was in the inside, I was well positioned. I saw Cavendish passing me and he swerved to the right and I needed to brake to avoid collision. It's not up to me to decide if he made a mistake," said a disgruntled Kittel.
The 31-year-old Cavendish took a different view: "When I saw Marcel Kittel taking the lead with only four guys two kilometers before the end, I understood it would kill him ultimately," he told the official Tour website.
"I just had to wait for him to lose some speed," he added.
A four-man group compromised the breakaway action on the 208.5km from Montelimar and had whittled down to two men, Jerome Roy (FDJ) and Martin Elmiger (IAM Cycling), as the peloton sped up.
The brave pair were caught just over 3km from the finish and it left the sprinters and their teams to jostle for position with Dimension Data's Cavendish top of the pile again, his 30th stage win on the Tour de France.