The 26-year-old from the Isle of Man came from behind to belatedly open his 2011 Tour account on the crash-strewn 164.5-kilometres fifth stage from Carhaix to Cap Frehel on the Brittany coast.
Cavendish, who is reportedly set to join Team Sky at the expiry of his HTC-Highroad contract, came off the wheel of fellow Briton Geraint Thomas before accelerating around to take the win ahead of Philippe Gilbert (Omega Pharma-Lotto), who inherited the green jersey from previous incumbent Jose Joaquin Rojas (Movistar), who finished third.
Cavendish later compared the surprise win with his 2009 success in Aubenas, dedicated his win to his recently-deceased dog, accused former team-mate Andre Greipel of striking him and rebuked a journalist for a factually inaccurate question.
In an interview with French TV, Cavendish also pointed to his head and said: “Most of my problems are in here. But once I get settled I’m normally all right and it gets easier.
“I’m just passionate about the sport. I just love to win.
“Maybe people don’t like my character so they try to do things not in a sporting way by disqualifying me or taking points from me.”
Cavendish was later asked to expand on his point, but stopped short.
He added: “If I go into that, we won’t get out of here tonight. But it’s what makes me tick.”
It was an interesting end to a hectic day which saw RadioShack leader Janez Brajkovic taken to hospital with concussion and a suspected fractured collar bone after crashing out of the Tour and Nicki Sorensen, the Danish champion, pulled down by a photographer’s motorbike.
Sorensen’s team leader Alberto Contador (Saxo Bank-SunGard) and Team Sky’s Bradley Wiggins were among those also to fall, while Tom Boonen (QuickStep) had a heavy tumble on the tarmac and suffered for much of a day which saw Thor Hushovd (Garmin-Cervelo) retain the race leader’s yellow jersey.
Ireland’s Nicolas Roche is in 24th place overall, 1 minute and 12 seconds down, after the AG2R La Mondiale rider finished in 20th place yesterday.
The finale along narrow, undulating roads was always going to be challenging and so it proved, with numerous attacks attempted and foiled as the stage ended in a sprint finish.
Cavendish was supported by team-mates Matt Goss and Tony Martin before rounding Thomas and sealing victory. It was a move which could become common in 2012.
Cavendish added: “It was a difficult win and it was one I had to give 100% before. It’s taken a lot out of me.”
The Briton has spoken of silencing doubters in recent weeks, believing he has been written off.
He added: “It’s always sweet to silence ignoramuses.
“They know who they are. It will happen again.”
Today’s 226.5km stage from Dinan to Lisieux and Friday’s 218km stage from Le Mans to Chateauroux are likely to end in sprint finishes and Cavendish could add to his prolific record.