Holland will on Monday meet Chile in a play-off for top spot in Group B after World Cup holders Spain crashed out of the tournament.
The Oranje survived a scare to beat the Socceroos 3-2 and claim a second win, following their opening 5-1 victory over Spain, who tumbled out by losing to Chile.
The defeat of Australia was not as straightforward as the win against Spain, but incoming Manchester United manager Louis van Gaal had no doubts his Holland side would prevail even prior to substitute Memphis Depay's decisive strike.
"I'm not relieved, because I believe in the second half we played better than Australia," Van Gaal said on fifa.com.
"In the first half they played better, but in the second half we had five, six, seven chances.
"I expected us to win. When (Australia's Mathew Leckie) missed that chance, I said to Patrick Kluivert, 'We're going to win this match.'"
With qualification assured, at stake now is who finishes top, thus likely avoiding playing hosts Brazil in the last 16.
Holland will be without captain Robin van Persie, who scored his third of the tournament but was also booked, earning a suspension for the final group game.
Defender Bruno Martins Indi could also be out after he was taken off on a stretcher after landing heavily following a poor Tim Cahill tackle.
Cahill's exquisite volley had levelled matters almost immediately after Arjen Robben gave Holland the lead.
Van Persie then swiftly cancelled out Mile Jedinak's penalty before Depay's winner.
Cahill was thrilled with his strike, but rued a missed opportunity.
"The ball was sitting beautifully," he said on itv.com.
"It just felt so right to hit it. I hit it sweetly and it's what it's all about. Defining moments."
Cahill will miss Australia's final match with Spain through suspension, effectively ending his World Cup career.
He added: "It is what it is. I leave everything on the pitch."
But Cahill was proud of the display.
"It was an amazing performance," he added.
"We knew this was a chance. We thought we could win this game.
"We got close. We'll earn a lot of respect."