Riders will see more officers on the trains and platforms but commute times should not be affected.
"We have uniformed officers in increased number in our subway system as well as police officers," said TTC spokeman Brad Ross.
TTC riders are also being asked to play a role in keeping their fellow passengers safe.
"The message really is simple, if you see something, say something," said Ross.
That slogan may sound familiar to anyone who's been to New York in recent years. It was coined after the attacks of Sept. 11, 2001, to increase vigilance on public transit.
CBC's Linda Ward was at Toronto's Union Station on Thursday and noticed an increased level of security.
"I've seen police officers and security guards patrolling the halls," she reported. "And there's also announcements over the PA system saying that due to the events in Ottawa and Quebec, there will be more transit officers and police officers on trains, buses and in stations."
Officials from both GO Transit and the TTC say there have been no specific threats made against their vehicles or property.
Passengers hurrying to work told CBC News they were not worried.
"I'm not scared or anything," one passenger told Ward. "Maybe just a heightened level of awareness."
In a news conference yesterday, police chief Bill Blair said there will be a very visible increase in police presence in public spaces such as court houses, consulates and government and military buildings.