Hesjedal, from Victoria, and Hughes, of Winnipeg, will be joined in London by Montreal’s Joelle Numainville and Yellowknife’s Denise Ramsden.
Hesjedal is Canada’s lone entry in both the men’s road race and the time trial. On the women’s side, Hughes and Ramsden will race in both events, while Numainville competes in only the road race.
Hesjedal made history last month when he won the prestigious Giro d’Italia, becoming the first Canadian to capture one of cycling’s three so-called grand tours, which also includes the Tour de France and the Vuelta a Espana.
The 31-year-old Hesjedal, who finished sixth in last year’s Tour de France, will compete in this year’s event from June 30 to July 22, giving him little time to rest before the Olympics. The men’s road race takes place on July 28, followed by the time trial on Aug. 1.
This will be Hesjedal's third Olympic appearance. He competed in the mountain bike event in 2004, and in both road events in 2008.
“I am honoured and excited to represent Canada in the Olympic Games. It is my hope that the sport of cycling continues to grow in Canada and that the spirit of the Olympics shines an even greater spotlight on it," Hesjedal said in a news release.
Hughes, 39, is the only Canadian to win medals in both the Winter and Summer Olympics. She captured a pair of bronze medals in cycling at the 1996 Summer Games in Atlanta before switching to speedskating and winning four more medals, including a gold at the 2006 Winter Olympics in Turin and a bronze at the 2010 Vancouver Games.
If Hughes reaches the podium in London — her sixth Olympics — she’ll break a tie with speedskater Cindy Klassen for the most career Olympic medals by a Canadian.
"After 12 years, I am excited to compete again at the Summer Olympics," Hughes said. "I am heading to London with the confidence that I could not be better prepared to perform at my best."
The Canadian Olympic mountain bike team was announced Wednesday, with reigning world champion Catharine Pendrel topping the list.
Last week, the track cycling team was unveiled, topped by medal contenders Tara Whitten and Zach Bell.