Applause rang out for the guardian of the cradle of Canada's democracy - who bears the assembly's ceremonial mace - followed by a prayer, the national anthem, a moment of silence.
"The objective of these attacks was to instill fear and panic in our country and to interrupt the business of government," Harper said in the Commons.
"Well, members, as I said yesterday, Canadians will not be intimidated.
Harper then crossed the floor of the Commons to shake Vickers' hand, and hug opposition leaders.
Yesterday, a man shot and killed a Canadian soldier who was mounting a ceremonial guard at a war memorial in downtown Ottawa before storming into the nearby parliament building.
Shots rang out as he rampaged through the halls of the building, and Vickers has been credited with taking him down.
