Pallekele - Pace spearhead Mitchell Starc claimed three wickets to help Australia dismiss Sri Lanka for a modest 195 in 40.2 overs in the fifth and final one-day international on Sunday.
The hosts, who have already lost the series 1-3, got off to a solid start but lost wickets regularly in Pallekele.
Openers Dhananjaya de Silva and Danushka Gunathilaka put together a 73-run partnership, Sri Lanka's best first-wicket stand of the ODI series.
But Australia's persistent attack took three wickets in nine deliveries to rattle the Sri Lankan top order with a mini-collapse.
Left-arm pacer James Faulkner had de Silva trudging back to the pavilion for 34. The batsman was beaten by the angle of the ball, giving a catch to mid-on in the 14th over.
Leg-spinner Adam Zampa struck in the very next over to have Gunathilaka bowled round his legs for 39, after the batsman attempted a sweep while exposing his leg stump.
Starc, who was brought back for his second spell in the 16th over, then had stand-in skipper Dinesh Chandimal caught behind for one.
Kusal Mendis (33) and Upul Tharanga put on 43 for the fourth wicket to try and rebuild the innings, but the wickets kept tumbling.
Kusal Perera, who scored 14, may have suffered an umpiring error after reviewing his lbw dismissal off Travis Head.
TV replays suggested he had got an inside edge on to his pad but third umpire Michael Gough thought otherwise.
The rest of the batting failed to put up any resistance as Starc returned to help remove the tail.
Left-armer Starc bowled Dilruwan Perera for five and Suranga Lakmal for nought. But Amila Aponso survived the hat trick ball in the 37th over.
Number eight Sachith Pathirana came up with a 32-run cameo to add some runs to the Sri Lankan scorecard but got no support from the other end.
Spinners Zampa and Head took two wickets each while pacers Hastings, Faulkner and Scott Boland got one apiece.