The West Indies were bowled out for 152, with Australia comfortably chasing down the target with six wickets and 117 balls to spare.
Ashton Agar was named Player of the Match after taking 2-31, with the wickets of top-order pair Shai Hope and Darren Bravo, before a steadying 19* alongside Matthew Wade who made 51* from 52.
The West Indies had dominated the T20I series against Australia 4-1, but struggled in the 50-over format with the bat, managing only 123 in the first ODI too, leaving captain Kieron Pollard fuming with the standard of the pitch.
“Coming here to Barbados, I think both teams struggled on the pitch and I think that’s unacceptable for international cricket,” Pollard said.
“We’re not going to make excuses. We accept that we batted badly but I don’t think the scores that we have gotten in this three-match series, with two top international teams, I think that’s very embarrassing for us as a people.
“Coming from St Lucia to this, I think it’s absolutely ridiculous.”
Stand-in Australia skipper Alex Carey, who took over from the injured Aaron Finch, revelled in his side’s victory.
“We understood the conditions and for the batters to score 150, it was a great target to get,” Carey said.
“It’s pretty nice to throw the new ball to Hazlewood and Starc. Ashton Agar coming into the group was fantastic today.
“Adam Zampa throughout the last 24 months has been brilliant. Ashton Turner did a great job as well in these conditions.”