Victoria native Hesjedal won the 2012 Giro d'Italia, becoming the first Canadian to win a Grand Tour race. He leads a Garmin-Sharp team also featuring USA Pro Challenge winner Christian Vande Velde and three-time Tour de France stage winner David Millar.
Slovakia's Sagan, one of the sport's top sprinters, won the points classification in both the Tour de France and Tour de Suisse in 2013.
Australian Evans won the 2011 Tour de France and finished second in 2007 and 2008.
"To have a former Tour de France winner Cadel Evans, one of the most prolific winners today in professional cycling in Peter Sagan, and Canadian cycling hero and a Tour of Italy champion Ryder Hesjedal in the same race is amazing, and will make for a spectacular experience for everyone involved," race executive director Duane Vienneau said in a statement.
The race begins Sept. 3 in Edmonton and ends Sept. 8 in Calgary.