The police had been called to the property just before noon, apparently in response to a medical complaint.
"We've been informed of the tragic news that Barry and Honey Sherman have unexpectedly passed away", Apotex, a generic-drug maker, said in a statement Friday. He is estimated to be worth almost $5 billion and is believed to be the 15th richest person in Canada.
The fortune of the Sherman's is estimated to be $3.2 billion.
Canadian advocacy group Democracy Watch criticised Sherman a year ago for involvement in a fundraiser for the Liberals while registered as a government lobbyist.
"Two weeks ago it gave me enormous joy to present a Senate medal to one of the kindest and most beloved members of Canada's Jewish community", Frum wrote.
According to BBC, Mr Sherman was the founder and chairman of pharmaceutical giant Apotex, which sells generic medicines around the world.
Honey was on the board of governors at York University, the Baycrest Foundation and Mount Sinai Hospital.
The couple had four children.
The investigation is in its initial stages, but the deaths are not being treated as homicides, CNN quoted Constable Hopkinson, as saying. The police confirmed there were no signs of any forced entry. They would not confirm that the two bodies were the Shermans but say they are treating the deaths as "suspicious".
Results of a postmortem examination will indicate whether the Shermans' deaths will be investigated as a homicide, Hopkinson said. The situation otherwise is the same.
Prime Minister Justin Trudeau wrote on Twitter that he and his wife Sophie "are saddened by news of the sudden passing of Barry and Honey Sherman".
"I am beyond words right now", Ontario health minister Eric Hoskins said in a tweet.
"Barry and Honey were kind, good people who will be greatly missed". Incredible philanthropists, great leaders in health care.
"Patients around the world live healthier and more fulfilled lives thanks to his life's work, and his significant impact on healthcare and healthcare sustainability will have an enduring impact for many years to come", the company said.