Liberal Leader Justin Trudeau, NDP Leader Thomas Mulcair and Bloc Quebecois Leader Gilles Duceppe all attended the celebration.
Trudeau mingled briefly with the crowd and described the Fete Nationale as an event that "brings Quebecers together" to celebrate "our local culture and our magnificent French language."
Mulcair described the event as "a way of celebrating everything we have in common and to realize how lucky we are to live here."
Duceppe waved a small Quebec flag as he marched alongside Montreal Mayor Denis Coderre and Parti Quebecois leader Pierre Karl Peladeau.
He highlighted the nationalist undertones of the holiday, which was formerly known as St-Jean-Baptiste Day.
"I think it's a beautiful thing that people are walking behind this parade expressing what we are, just as Canadians do July 1st, Americans do July 4th, and French on the 14th (Bastille Day)," Duceppe said.
The parade route along St-Denis street was lined with Montrealers enjoying the blue skies and cheering on the floats and costumed dancers, many dressed in blue and white and celebrating this year's theme: "Quebec, a land where life is good."
Prime Minister Stephen Harper was also in Quebec. He participated in a photo op and delivered a speech in the Beauce region near Quebec City.
On Tuesday night, several popular Quebec musicians entertained a crowd of tens of thousands on the Plains of Abraham in Quebec City while other artists performed in Montreal's Place des Festivals.
In all, some 700 events took place across the province today to mark the 181st edition of Fete Nationale.
Various francophone communities across Canada also held celebrations.