New Zealand boasted a 16-2 lead at half-time before winger David Fusitua put in a stellar second-half performance as he crossed for a hat-trick of tries.
The Pacific Islanders are now likely to face Lebanon in the quarter-finals, unless France can pull off a shock victory over England on Sunday, while New Zealand finished second in the group and will take on Fiji in the knockout stages.
Tonga head coach Kristian Woolf is optimistic of his side’s chances of winning the tournament after making history against the tier-one nation.
"Look, I'm not going to sit here and say 'no'," Woolf said, when asked whether his side could win the competition.
"(But) Australia's a whole different beast. They've won so many internationals because of the way they play and the way they just suffocate you.
"We've got a long, long way before we play them. We've got to worry about Lebanon next week then we've got to worry about what happens after that as well."