GROS ISLET: West Indies' stand-in captain Nicholas Pooran won his first toss of the series and decided to bat against Australia in the final Twenty20 match.
Then opener Evin Lewis took over.
Player-of-the match Lewis scored 79 runs off 34 balls, including 9 sixes, to put the Caribbean side well on its way to its fourth win in the five-match series.
Despite a late collapse, the West Indies scored its highest total of the series — 199 for eight.
Australia finished with 183-9 to give the home side a 16-run win.
The visitors were looking strong in reply when they lost two wickets for five runs, including a spectacular one-handed diving catch at long-on by Fabian Allen to remove captain Aaron Finch for 34.
Andre Russell and Sheldon Cottrell took three wickets each for the West Indies.
Pooran added 31 to Lewis' dominant batting display and the West Indies were at 168-4 when they lost 4-25 before tailender Hayden Walsh Jr. hit a six to end the home side's innings.
Andrew Tye made his first appearance of the tour and led the Australian bowlers with 3-37 while Adam Zampa and Mitch Marsh added two wickets each.
Australia, which won the fourth match after losing the first three, made four changes.
Leg-spinner Mitchell Swepson was also named for his first game on tour while Josh Hazlewood and Josh Philippe returned to the side.
Mitchell Starc was rested and Riley Meredith, Dan Christian and Ashton Turner were also left out.
Phillipe opened and was out for 1 after four deliveries.
The teams will now play three one-day internationals at Bridgetown, Barbados.
The first match is scheduled for Tuesday.