A 17th-minute Kaku penalty was followed by goals from Miguel Almiron, Matias Galarza and Alexandro Maidana on Friday (Saturday AEST) in the capital Asuncion.
The South Americans, who finished qualifying in sixth place, take on the Socceroos at Levi's Stadium in Santa Clara, California on June 26 after earlier clashes in Group D against the United States and Turkey.
In Montreal meantime, Chiedozie Ogbene's equaliser ensured the Republic of Ireland continued their good run of results as they drew 1-1 with World Cup co-hosts Canada.
Ogbene reacted quickest to slot home after Troy Parrott's penalty was saved as Ireland ended their season with another solid result.
They have lost just once in their last eight games, including five wins, with the only defeat against the Czech Republic on penalties.
Canada went ahead midway through the first half when a corner was flicked on by Parrott and found the Irish net via the unfortunate Jake O'Brien.
Ireland were given a route back into the match just before the hour when Jamie McGrath was caught by a high foot in the box by Cyle Larin.
Parrott's penalty was saved by Maxime Crepeau, but Ogbene won the race to sweep the loose ball into the net.
Elsewhere, World Cup finalists Saudi Arabia beat Puerto Rico 3-0 in Austin, Texas but Haiti were beaten 2-1 by Peru in Miami, Florida.
With AAP.
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