Armitage, third Keith Glover, second Randy Ponich and lead Wilf Edgar stole two points in the second end before pulling away in the opening draw at the Grant-Harvey Centre.
"They weren’t used to that kind of draw weight and of course we are, and you could see it right away," said Armitage. "It was a good start for us, but we have Finland this afternoon so that’ll be a good test for us."
It’s the first time Armitage and his teammates from Red Deer, Alta., have represented Canada at an international event.
"There is some pressure wearing the Maple Leaf, and there are some good teams here," said Armitage. "The fact that Canada has won this seven of the 11 years and all that, you think about it. There’s no way around it.
"It’s a world curling event and you don’t want to go out and stink it up for your country, that’s for sure."
In women's play, Canada's Cathy King and her St. Albert, Alta., teammates of third Carolyn Morris, second Lesley McEwan and lead Doreen Gares will play Ireland’s Mary O’Kane later Saturday.
The world seniors are being staged jointly with the 2013 world mixed doubles championship.
The Canadian mixed doubles duo of Robert Desjardins and Isabelle Neron from Sagueuay, Que., will open against Italy.