City dominated possession throughout the game but squandered a host of chances before Evans finally broke the deadlock in the 84th minute.
Evans, who has yet to make his Premier League debut for City, collected a ball from Martin Demichelis and curled a shot from 30 yards out into the top right-hand corner.
City boss Manuel Pellegrini included first-team regulars David Silva, Yaya Toure and Vincent Kompany alongside the likes of Dedryck Boyata, Seko Fofana and Willy Caballero in his starting line-up.
A crowd of more than 23,000 fans at BMO Field saw David Silva and Wilfried Bony twice go close in the first 30 minutes, while Edin Dzeko also fired just wide for the visitors.
Toronto barely mustered a shot in the first half and it was a similar story after the break when the introduction of Sergio Aguero gave City extra pace up front.
The hosts’ best effort came in the 76th minute when Manny Aparicio struck the post.
Evans’ goal ensured that City, who finished off the Premier League season with six successive victories, made a winning start to their North American tour.
They are now scheduled to face Houston Dynamo on Friday, although flooding in the Texas city could threaten the fixture.