The Canadian defence was ripped apart on all three goals at Craven Cottage, the west London home to English Premier League side Fulham.
The loss stretched Canada's winless streak to 12 games (0-9-3) during which time it has been outscored 24-2. The Canadian men haven't scored in their last eight outings, a drought that now stands at 12 hours 32 minutes.
The young Canadians showed signs of life in the first half, despite yielding a first-minute goal against experienced, motivated opposition. But the second half was all Australia.
The Socceroos, meanwhile, snapped a four-game losing streak in their first match since Holger Osieck, a former Canadian national team manager, was fired as coach.
"It's obviously tough when you give up an early goal like that," Canada captain Dwayne De Rosario said. But we knew that Australia was in a position that they had a lot to prove obviously with the recent sacking of their manager."
After successive 6-0 losses to Brazil and France, a date with a green Canadian side was a welcome tonic for the Australians.
Australia is ranked 53rd in the world, compared to No. 106 for Canada.
Australia stroked the ball around in the first half, controlling close to 60 per cent possession with veteran midfielder Mark Bresciano pulling the strings for the Socceroos.
Still Canada had several good chances on the counter-attack later in the half.
The Canadians fell behind within the first 30 seconds when Kennedy headed in a chipped cross from Bresciano that left goalkeeper Milan Borjan rooted to the spot.
The 33-year-old Australian midfielder, a veteran of Italy's Serie A who now plays for Qatar Stars League side Al-Gharafa, got a break when the ball bounced off a Canadian straight to him. But Canada's central defence was flat-footed on the play.
The six-foot-four Kennedy plays for Nagoya Grampus Eight in Japan.
Canada came close to equalizing in the sixth minute but Mitch Langerak made a fine reflex save to deny Simeon Jackson after David Edgar headed on a Marcel de Jong free kick across the goal.
De Rosario also had a chance in the 15th minute after Edgar charged down the right flank, but his cross was slightly behind the D.C. United star and the shot did not find its target.
Bresciano undressed the Canadian defence again in the 23rd minute but his one-two with Kennedy was ruled offside.
Langerak had to be sharp in the 30th to palm a Tosaint Ricketts header over the bar.
"I think we got the balls in some areas and (Langerak) made some good saves," De Rosario said. "It was a little unlucky but the main thing was we were starting to push and take some initiative and find some pokes at goal. That's the positive we can take from that. A game like this is a good opportunity for us as a national team to see where we are moving forward."
De Rosario earned his 75th cap in captaining Canada, which started with a backline of Nik Ledgerwood, Doneil Henry, Adam Straith, and de Jong in front of Borjan.
The centre back pairing featured 23-year-old Straith, who plays in Germany for Wehen Wiesbaden, and 20-year-old Henry, who plays for Toronto FC.
The midfield featured Ricketts, Julian de Guzman, Edgar, and Jackson supporting forwards Iain Hume and De Rosario.
Canadian coach Benito Floro was without influential midfielder Atiba Hutchinson, who returned to his Turkish club Besiktas late Saturday after arriving in camp with a minor injury.
Floro moved up Edgar, a defender normally, into midfield.
There were more midfield woes when de Guzman had to exit in the 25th minute with an injury. He was replaced by Kyle Bekker.
Both coaches made changes in the second half with Floro bringing on youth in the form of Jonathan Osorio, Stefan Cebara, Russell Teibert, Ashtone Morgan and Samuel Piette.
Canada mustered little offence, however, and Australia dominated as the game wore on.
"In the second half the young players did not play well because the opponent was physically very powerful," Floro said. "They made a big press and we didn't have any chances at goal. It's necessary with the young players because we need to give them international experience. This is the problem for us."
The only way to improve our level is to play a lot of matches and by training, not only with these players but also the younger ones to teach how we want them to play.
Edgar took over as Canadian captain when De Rosario went off.
Australia doubled its lead in the 52nd minute off a corner. Henry's clearing header went only as far as Rhys Williams, whose shot bounced off the turf before Vidosic redirected it in with his head just in front of Borjan.
Substitute Leckie made it 3-0 in the 78th minute when he outjumped both Canadian central defenders to head home a Carney cross.
It was Floro's third game in charge. Canada played to a 0-0 draw and 1-0 loss to No. 150 Mauritania last month.
Osieck was fired in the wake of Australia's lopsided losses to Brazil and France. Interim coach Aurelio Vidmar was put in charge.
"Great way 2bounce back from the team with a win over Canada," Australia forward Tim Cahill said on Twitter. "Youngsters were brilliant. Credit to Vidmar getting us back on track."
Australia was captained by veteran defender Lucas Neill, who won his 95th cap.
Canada last won in October 2012 when it defeated Cuba 3-0 in Toronto in October 2012. Canada has not scored since a Marcus Haber goal in a 2-1 loss to Japan in Doha on March 22.
Australia wasn't much better coming into Tuesday's game, having lost four straight and gone winless in its last five matches — during which it was outscored 19-5.
NOTES — Craven Cottage officials did their bit to make Canada feel at home by playing the Barenaked Ladies and Tragically Hip during the warmup.