Warner's 55 not out saw Australia home with almost 25 overs to spare after the West Indies earlier collapsed from 50 for one to 116 all out from 32.3 overs.
Australia then wasted little time in getting to the modest target, Warner anchoring the effort to ensure a victory that was never in doubt despite the loss of three wickets for seven runs with the end in sight.
Spinners Sunil Narine, with two wickets in one over, and Sulieman Benn caused the discomfort but it was not enough to save the hosts.
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The emphatic victory earned Australia a bonus point to move ahead of the West Indies in the three-team standings before Tuesday's final game at Providence against South Africa.
"Our batting is a real concern," said West Indies coach Phil Simmons.
"The bowlers and fielding side are doing a great job but we need to get it together with the bat for the next two matches in St Kitts."
Boosted by a four-wicket win in the tournament-opener against the South Africans at the same venue two days earlier, the West Indies plummeted back down to earth at the feet of the World Cup-holders, whose frontline spinners Nathan Lyon and Adam Zampa did the bulk of the damage with three wickets apiece after the usual effective opening burst from Mitchell Starc.
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"I really enjoyed it out there on that pitch," Zampa enthused after his performance.
"South Africa will be a big challenge though on Tuesday with so many quality batsmen."
Playing his first international match for more than six months after being sidelined by injury, the left-arm fast bowler breached the defences of openers Andre Fletcher and Johnson Charles to finish with figures of two for 37 from nine overs.
He showed signs of rustiness in delivering five wides and a no-ball, however his lethal pace proved more than a handful for the West Indies top order.
Starc's tally of ODI wickets is now at 92 in his 47th match and should he take eight more before the end of this competition he will eclipse Pakistan's Saqlain Mustaq for the record as the fastest to 100 wickets in terms of matches played in this format of the international game.
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Charles topscored with a chancy 22 while all-rounder Carlos Brathwaite was last out for 21, Aaron Finch taking the catch at long-on to give Zampa his third wicket.
Notwithstanding the turgid surface, the home batsmen contributed to their swift demise with a succession of poor shots, exemplified by Darren Bravo's loose cover-drive at seamer Mitchell Marsh which offered a straightforward catch to Zampa at cover.
Lyon, the experienced off-spinner, had an almost instant impact in disposing of Marlon Samuels and Kieron Pollard off successive deliveries. Pollard, whose unbeaten 67 guided the West Indies to victory over the Proteas two days earlier, attempted a heave over long-on to be taken by Warner on the boundary.
Jason Holder gave mystery spinner Narine first use of the new ball from one end in hopes of an immediate breakthrough at the start of the Australian reply, but it was left to the captain to separate the opening pair as Warner and Finch got off to a flying start with a succession of boundaries on both sides of the wicket.
They had put on 44 by the eighth over when Finch was leg-before for 19 in Holder's first over, giving the gangling Barbadian his 50th wicket in One-Day International cricket.
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