Chris Gayle produced his best knock since his return to the international side, with 67 from 38 balls as the West Indies cruised in the chase, winning with 31 balls to spare.
Stand-in captain Nicholas Pooran (32* from 27 balls) finished the job with back-to-back boundaries off Riley Meredith (48-3) to seal the series victory with two games to play.
Australia captain Aaron Finch won the toss and elected to bat first this time, with his batsmen failing to capitalise on several starts, only managing 141-6.
Moises Henriques top scored with 33, hitting Australia's only two sixes, with Hayden Walsh restricting them with 18-2 from four overs.
The improved Mitchell Starc (18-1 from four) dismissed Andre Fletcher early, bringing Gayle to the crease and the 41-year-old was at his best.
Gayle hit several lusty blows, including seven sixes and four fours in his knock, before edging to wicketkeeper Matthew Wade off Meredith.
RETURN TO FORM FOR GAYLE?
Gayle has made it clear that his return to the West Indies, after two years away, has been inspired by competing at the T20 World Cup later this year.
Despite strong Indian Premier League form, he has struggled upon his return to the international arena, managing only 102 runs in nine innings.
The veteran left-hander made his first T20 International half-century since 2016 with his knock at first drop on Monday.
"From a personal point of view, you all knew I was struggling with the bat, but to be get some runs today it's very pleasing," Gayle said. "I want to dedicate these runs to my teammates, especially Kieron Pollard. He gave me the pep talk I needed."
Gayle made 288 runs in seven innings at an average of 41.14 in the 2020 IPL, before scoring 178 runs in eight knocks in the 2021 edition.
"Looking back, when I got back into the West Indies team against Sri Lanka, I was trying to play a different role, than play Chris Gayle himself," Gayle said. "I didn’t get the runs but the guys rallied around me. It's coming on, my main focus is the World Cup."
AUSSIES T20I WOES CONTINUE
Australia continue to struggle in the shortest format, having been comfortably beaten in all three matches in the series.
Finch, who made 30 from 31 deliveries at the top of the order, felt there was a clear theme to address among the losses.
"Same as the other games, we haven’t had the top order go on deep into the innings," Finch said. "It's been quite similar the whole way through. Credit to the West Indies, they bowled beautifully, especially at the back end."
Australia have only managed scores of 127, 140 and 141-6 in the three T20Is this series, bowled out on both occasions when they have chased.
"We would’ve liked more runs, no doubt," Finch added. "That comes down to the top order not going through. If one of your top four is there through the end you put pressure on the bowlers."