Maâ€™a Nonu scored the sole try of the match and Piri Weepu kicked 12 points as the All Blacks swamped Australia to prevail in this brutal encounter.
Australia began proceedings by playing straight into New Zealandâ€™s hands as fly-half Quade Cooper put his kick-off directly into touch and Piri Weepu kicked deep into Australian territory from the resulting scrum as the All Blacks sought the initiative.
Israel Dagg had already looked dangerous for Graham Henryâ€™s men on his first piercing break, but it was his second that led to the first try of the night.
The Crusaders full-back broke on the outside and shook off attention from Cooper before expertly off-loading to Nonu who went over.
Piri Weepu missed the conversion, and quickly followed it by missing an easier penalty chance, but registered points with his third attempt after David Pocock was penalised.
The All Blacks were sweeping forward in waves but Australia were quick to respond when James Oâ€™Connor fielded a wayward kick and passed to wing Digby Ioane, whose powerful break led the Australians into New Zealand territory for the first time. The search for gaps proved fruitless before a ruck infringement from McCaw gave Oâ€™Connor the chance to claim Australiaâ€™s first points.
A collapsed scrum allowed Weepu to extend New Zealandâ€™s lead and Aaron Cruden added a drop-goal following further pressure. An excellent kick from Will Genia gave Australia good field position and Cooper replied with a drop-goal of his own but a soft penalty from the Wallabies gave Weepu an easy kick to restore the eight-point gap going into half-time.
Weepu extended New Zealandâ€™s lead when Pat McCabe was penalised for holding on early in the second half.
Acknowledging the increasing points gap, Australia responded well and began a large spell of possession but New Zealandâ€™s defence held firm and halted each Australian attack with several morale-boosting hits.
A side-entry penalty against Stephen Moore went unpunished after a Weepu kick drifted wide, but New Zealand were slowly gaining superiority in the close-quarters.
Australiaâ€™s David Pocock had been spoken of as one of the tournamentâ€™s shining lights, yet with little help from his fellow forwards the Western Force flanker was facing a losing battle.
A Pocock turnover quickly followed by another from Richie McCaw, himself a handy open-side in his own right, was symptomatic of the way the tide turned against Pocock and his teammates as McCaw began to rule the breakdown.
New Zealand were dominating all areas of the forward battle, and their hugely experienced front five were rewarded for their powerful scrum with two penalties. The first was missed by Cruden, taking duties from Weepu after he had left the field, but Weepu returned to take full advantage of the second after a jubilant NZ pack took the ball against the head.
Weepuâ€™s kick looked to have put the All Blacks out of reach but a late Sonny Bill Williams shoulder charge saw the centre sin-binned and provided a chance for the Wallabies to kick to the corner.
However, the All Blacks repelled Australiaâ€™s efforts oncemore to clinch their place in the final and send Eden Park wild.
Speaking after the game, New Zealand captain Richie McCaw said: â€œWe realised that we were going to have to front up and be on the job for 80 minutes. Every single man out there did their bit tonight.â€
New Zealand fans will have been relieved when the Crusaders flanker confirmed his foot should be fine for next week, and the team will need him as they seek their second World Cup victory and first since 1987.
New Zealand: Israel Dagg; Cory Jane, Conrad Smith, Ma’a Nonu, Richard Kahui; Aaron Cruden, Piri Weepu; Tony Woodcock, Keven Mealamu, Owen Franks, Sam Whitelock, Brad Thorn, Jerome Kaino, Richie McCaw (capt), Kieran Read.
Replacements: Andrew Hore (for Mealamu 64), Ben Franks, Ali Williams (for Whitelock 57), Victor Vito, Andy Ellis (for Weepu 57), Stephen Donald, Sonny Bill Williams (for Nonu 73).
Australia: Adam Ashley-Cooper; James O’Connor, Anthony Fainga’a, Pat McCabe, Digby Ioane; Quade Cooper, Will Genia; Sekope Kepu, Stephen Moore, Ben Alexander, Dan Vickerman, James Horwill (capt), Rocky Elsom, David Pocock, Radike Samo.
Replacements: Tatafu Polota Nau (for Moore 66), James Slipper (for Kepu 21), Rob Simmons (for Vickerman 60), Ben McCalman (for Samo 60), Luke Burgess, Berrick Barnes (for McCabe 48), Rob Horne (for Faingaâ€™a 63).
MORE: The latest football news
MORE: The latest tennis news