The Credit Agricole rider was unaffected by a loose dog which brought down a host of cyclists and burst past a number of big-name sprinters on the climb to the finish.
Wearing the Norwegian flag proudly on his cycling vest, Hushovd held off a strong challenge from Kim Kirchen of the Fassa Bortolo team.
After 168 kilometres of mostly mundane racing, punctuated only by the curious incident of the dog in the peloton seven kilometres from home, the eighth stage developed into an all-out battle for supremacy.
Kirchen, from Luxembourg, looked to have the stage wrapped up as he wriggled into the lead through the narrow roads of the Brittany town.
But Hushovd would not be denied and after taking second place from Australian Robbie McEwen, he kept on powering up the tricky ascent, which had been made all the more difficult by the steady rain which had left the roads slippery.
Race leader Thomas Voeckler, riding for Brioches La Boulangere, was among the pack.
In the overall rankings, Cofidis rider Stuart O’Grady of Australia ranks second only to Voeckler, with French youngster Sandy Casar of FDJeux.com now third.
After several impressive stage performances, Ireland’s Mark Scanlon had one of his less spectacular rides and finished in the second group, behind the main peloton.
Scanlon’s official classification was 122nd, but the AGR2 rider lost just 21secs on the main group which did not harm his overall standing. The Irishman is a competitive 55th overall.