Middle-order batsman Mike Hussey and Nathan Hauritz starred with the bat for Australia, but it was fast bowler Ryan Harris who stole the show with the ball.
Pakistan were right in the game when they had Australia at 77-3 and then at 110-4, but Hauritz launched a late attack to take the total to 277-8.
Hauritz arrived with the score on 190-6 in the 40th over, and helped Australia add 87 in the final ten overs, as he took advantage of the final Power Play to smash an unbeaten 53 from just 39 balls. Hussey compiled a solid 67 and took a back seat in their partnership of 80, The Sydney Morning Herald reports.
Already 3-0 down and facing an unlikely victory target, Pakistan struggled to cope with Harris's fast outswingers as the right-arm paceman found the edges of opener Salman Butt (0) and the out-of-form Younis Khan (six).
The visitors crashed to 4-29 in the 10th over as Kamran Akmal (17) and skipper Mohammad Yousuf (10) fell in the space of three balls.
Harris snared his second consecutive five-wicket haul and man-of-the-match performance as Pakistan was dismissed for 142 in the 38th over.
The 30-year-old recorded brilliant figures of 5-19 from 9.5 overs, while Peter Siddle took 2-31 to make a strong comeback from a back injury to help Australia to a 4-0 lead.