The All Blacks Sevens took third place after falling 19-21 to Argentina in the semifinals and then beating Fiji in the playoff game.
South Africa claimed its fifth consecutive final in Dubai by beating Argentina 12-7.
Forced to play the final day without captain Sarah Hirini, who had her leg braced after suffering a knee injury on the first day against the USA, the Black Ferns battled through each of their finals games.
The final, a repeat of last year's Dubai event, had all the intensity of a trans-Tasman contest, with Australia scoring after only 23 seconds of play when Bienne Tarita crossed for a try.
But Jorja Miller replied with two tries before the five-minute mark. However, Teagan Levi scored before halftime to give Australia a 14-12 lead and then scored soon after the restart to lead 19-12.
Miller completed her hat-trick of tries in the 11th minute, with Tenika Willison adding the conversion to level the score.
However, Maddison Levi had the final say after the Black Ferns conceded consecutive penalties to give Australia the foundation by scoring a converted try. The series champions attacked but could not break the Australian defence before the final whistle.
Australia captain Charlotte Caslick said after completing their fourth consecutive win in Dubai, "We wanted to hold the ball as much as possible because we know when they touch it they're dangerous. That was key for us – restarts and holding onto the ball."
In their quarterfinal, the Black Ferns conceded a try in the first minute when Andressa Alves crossed. Still, a quick response saw Portia Woodman-Wickliffe reply in the third minute. Three minutes later, Tenikia Willison upset the Brazilians after a scrum by stealing the ball and scoring under the bar to give them a 12-7 halftime lead.
Mahina Paul showed her speed when running away for a 10th-minute try, but Gabriela Lima scored for Brazil to close to 14-19. Kelly Brazier sealed the win just before full-time with her 100th career try for a 26-14 win.
It took desperate defence to hold out a determined Canada team in the semifinals.
Risi Pouri-Lane and Michaela Blyde scored in the second and fourth minutes, while Charity Williams cleared out in the third minute to open Canada's scoring.
The Black Ferns led 14-7 at the break, but Florence Symonds got Canada to 12-14 down after Stacey Waaka was yellow-carded for a high tackle, and then Carissa Norsten claimed the lead with three minutes to play.
However, Jorja Miller was introduced and immediately made her presence felt when running onto a reverse pass from Brazier to split the Canada defence to score under the posts. Canada wasn't done, and the Black Ferns were under defensive pressure when the final whistle blew.
The All Blacks Sevens had no problems in their quarterfinal against the USA, winning 40-0. They took their time to find their momentum, taking four minutes before Scott Curry scored the first try.
But Che Clark, Leroy Carter and Akuila Rokolisoa followed over the line in the fifth, seventh and ninth minutes for a halftime lead of 26-0. Tepaea Cook Savage scored in the 10th and 12th minutes to complete the win.
Against Argentina, the All Blacks Sevens conceded the first try when Matias Osadczuck scored in the fourth minute. But Che Clark and Leroy Carter scored in the fifth and seventh minutes for a 14-7 halftime lead. Rokolisoa extended the lead with a ninth-minute try.
But Argentina came home stronger with Agustin Fraga scoring in the 11th minute while Gaston Revol, 37, playing in his 99th tournament, scored the matchwinner as they gained a place in their first Dubai final.
In the third-place playoff against Fiji, both sides took time to settle. But once Joseva Talacolo scored in the seventh minute, the New Zealanders replied immediately with Rokoklisoa crossing for a halftime score of 7-7.
Cody Vai clinched the lead for the All Blacks Sevens with a 10th-minute try, only to see Manueli Maisamoa reply a minute later.
The win came down to an almost last-gasp movement when the ball was moved wide for Fehi Fineanganofo to charge through two defenders to get the ball over the line for a 17-12 win.
