Tries from Nehe Milner-Skudder and Ma’a Nonu had the All Blacks cruising 21-3 early in the second half before Ben Smith’s yellow card opened the door for Australia, who got back to within four points with tries by David Pocock and Tuvita Kuridrani.
But flyhalf Dan Carter, who missed most of the 2011 tournament through injury and who is retiring from international rugby after Saturday’s match, stepped up with an exquisite drop goal and a 50-metre penalty to put the result beyond doubt.
Replacement wing Beauden Barrett applied the black icing to the Kiwi World Cup cake with a late try which Carter converted to take his personal tally to 19 points
New Zealand have lost just three times in 54 matches since their triumph on home soil four years ago, and have won every World Cup match since losing to France in the 2007 quarter-finals.
“I’m pretty grateful to be where I am considering what happened four years ago,” said man-of-the-match Carter, who was also part of the unsuccessful 2003 and 2007 campaigns.
“I’m so proud of the team. To win back-to-back World Cups is a dream come true. It’s a pretty strong group of guys. We try to do things no other team has done before… it’s a special feeling to be part of such a great team.”
The previous six World Cup finals had produced seven tries between them and Saturday’s total of five was a record, eclipsing the four of the inaugural final when New Zealand beat France.
The sport’s superpower won the cup for a second time four years ago, also on home soil, and Saturday’s victory was their first overseas.
“We said four years ago that we get on the road again with this being the end goal, try and do something no-one else has done,” said captain Richie McCaw, who is likely to retire now having become the first captain to win the Webb Ellis Cup twice.
“I’m so proud of the guys. We lost a bit of momentum in the second half but we kept our composure and came back strong.”
New Zealand looked on their game from the start, zipping the ball sharply along the lines and creating quick ball at every ruck to keep the Wallabies on the back foot.
Their pressure enabled Carter to thump over three penalties to one from Bernard Foley to make it 9-3 after half an hour.
Australia were struggling to get their livewire backline moving and suffered a blow when they lost centre Matt Giteau to a head injury.
Their first-half misery was completed when brilliant handling by Conrad Smith, Aaron Smith and Richie McCaw fired the ball wide for Milner-Skudder to score the first try of the night.
Carter converted for a 16-3 halftime lead and it took only two minutes of the second half for New Zealand to effectively put the game to bed.
Replacement Sonny Bill Williams, on for Conrad Smith, delivered a trademark offload to Nonu and the centre tore through some soft defending and sprinted 30 metres to mark his 103rd and last New Zealand appearance with a killer try.
Australia, as always, refused to lie down and immediately roared back into the attack. Smith was sin-binned for a tip-tackle on Drew Mitchell, the first yellow card in a final, and from the resulting penalty Australia drove over the line with Pocock the man at the bottom.
That spurred the Wallabies on to greater efforts and they got their second try after 63 minutes when a probing kick by Will Genia bounced perfectly for Foley who fed Kuridrani to slide over. Foley slotted the conversion and Australia they were back to within four points.
The atmosphere at Twickenham ramped up but once again it was the cool head of Carter who regained control.
The flyhalf, whose dropped goal in the semi-final against South Africa set in motion a momentum shift that turned that tight match, slotted another despite being under huge pressure – only the eighth of his 112-cap test career.
Carter then applied the coup de grace with a 50-metre penalty to make it 27-17 with five minutes remaining before replacement winger Barrett sprinted on to collect a Ben Smith kick to score under the posts.
“It’s a great way to finish,” coach Steve Hansen said of Carter’s orchestration of the win. “You couldn’t script it any better.”