Flight AC682, with 90 people on board, touched down safely at Halifax's Stanfield International airport at around 6:30 p.m. AT, airport officials say.
The flight left Toronto's Pearson airport around 3:10 p.m. ET and declared an emergency as it made its way east.
Halifax airport spokesman Peter Spurway said there was a mechanical issue on the aircraft.
"It landed safely, which is fantastic, and now there is an assessment being done of the aircraft," Spurway said.
Air Canada will decide what's next for the passengers on the plane, he added.
Environment Canada declared a severe thunderstorm watch in the Deer Lake area on Wednesday that has since ended.
The plane involved is an Embraer 190.