The tourists limped to 220 thanks largely to an unbeaten century from Kieron Pollard, and Australia's victory never looked in doubt as opener Shane Watson (76) top-scored to lay the platform for the chase.
Wicketkeeper Matthew Wade (13) and all-rounder Glenn Maxwell (one) were the unbeaten batsmen as the home side won with 31 balls to spare.
Watson, who smashed a century in the previous game in Canberra, produced another dominant innings which thrilled the Sydney crowd.
The 31-year-old looked set for back-to-back tons until he was undone by a Tino Best delivery, which caught the edge through to wicketkeeper Devon Thomas.
Adam Voges (28), a late inclusion for the injured George Bailey, and Michael Clarke (37) both made strong contributions, with the skipper dismissed just before Australia reached their victory target.
Earlier, the West Indies made a dismal start to their innings, slumping to 55 for six inside the first 20 overs.
Top-order batsman Johnson Charles (nought), Kieran Powell (nine) and Darren Bravo (four) were all back in the pavilion inside eight overs as they fell victim to a firing Mitchell Johnson (three for 36).
Ben Cutting, playing just his second ODI, also caused havoc and finished with three for 45 as it looked like the tourists would be lucky to get to triple figures.
But a fighting knock from all-rounder Pollard, who finished unbeaten on 109, and spirited resistance from the lower order got them to a competitive target.
- Sports & Recreation
- Kieron Pollard
- Shane Watson