The Kangaroos then went 404 minutes without having their defence breached, the only points they conceded being one penalty apiece by Fiji and New Zealand.
Smith, who revealed the team had received a good luck message from cricket skipper Michael Clarke in the build-up to the final, said the defensive performance was a source of great pride.
"It is something that we can look to build on," said the Melbourne Storm hooker.
Australia have won the World Cup on a record 10 occasions, ahead of Great Britain (three) and New Zealand (one).
Won by topping a four-team group played in Sydney and Brisbane
Beat France 20-2 in Sydney
Beat Great Britain 12-7 in Leeds
Beat England 25-0 in Leeds
Beat Great Britain 13-12 in Sydney
Beat New Zealand 25-12 in Auckland
Beat Great Britain 10-6 in London (pictured above)
Beat England 16-8 in London
Beat New Zealand 40-12 in Manchester
Beat New Zealand 34-2 in Manchester
"We are very proud of the defensive effort since the first game. We were challenged by [coach] Tim Sheens and assistant coach David Furner to be the best defensive team in the tournament and I believe we have come away with that mantle."
Australia full-back Billy Slater was another to take satisfaction after the disappointment of the last World Cup.
"I don't know about banishing demons - we can't change the past - but I've always tried to put the past behind me and focus on improving my future," Slater told BBC 5 live.
"I haven't looked back too much but it is great to hold one of these medals and be a part of one of these sides. New Zealand deserved it in 2008 but I thought we deserved it today."
Asked whether he had seen a better Australian side, coach Tim Sheens said: "Not in my time. I am extremely proud. We came over and performed extremely well. It is a great privilege for me to coach this team."
Slater dedicates final tries to kids
Sheens has been in charge of the Kangaroos since 2009 but is now out of contract.
The 63-year-old refused to be drawn on whether he would sign a new deal, focusing instead on his team's performance against the Kiwis.
New Zealand coach Stephen Kearney admitted his team had been well beaten on the day and said it was the best performance by the Kangaroos he had seen.
"Australia's performance today was nothing short of outstanding, we could just not get ourselves into the contest," said Kearney.
"Their performance was pretty faultless and they gave us a real lesson. That is as good as I've seen them play."
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