Ireland's hopes of ending their tour with a rare win over a Tri-Nations side were dashed in Perth as Australia came from behind for a clear victory.
Australia (11) 37
Tries: Latham, Gerrard, Holmes, Gregan, Shepherd
Cons: Mortlock 3
Pens: Mortlock 2
Ireland (3) 15
Tries: O'Gara, N Best
Second-half tries by Ronan O'Gara and Neil Best had built a platform for an Irish win, but the Aussies hit back.
Mark Gerrard, Greg Holmes, George Gregan and replacement Cameron Shepherd all crossed as the Wallabies opened up Ireland's tired defence.
Chris Latham scored in the first half as Australia led 11-3 at the break.
After two encouraging displays ended in defeats to New Zealand, Ireland had targeted a better result against Australia.
But the home side had the better of the early exchanges and went ahead through a Stirling Mortlock penalty on 14 minutes.
The Wallabies stretched their lead midway through the half as Latham touched down for an 8-0 advantage.
O'Gara and Mortlock exchanged penalties as Australia maintained their eight-point lead at the break.
It was fly-half O'Gara, criticised for defensive flaws against the All Blacks, who sparked the Irish revival.
His high cross-kick was caught by Shane Horgan, who fed David Wallace and his pass was well taken by O'Gara for a fine try on 47 minutes.
The Irish struck again just three minutes later with Best's try in the left corner after good play by Andrew Trimble and Denis Leamy.
O'Gara slotted over a touchline conversion to put Eddie O'Sullivan's side 15-11 in front.
But the visitors' lead lasted barely five minutes as winger Gerrard broke through for a clincal first-phase try.
The Wallabies added further scores through loose-head Holmes, who pounced on a loose ball to race half the length of the field, scrum-half Gregan and Shepherd.
Australia: Latham; Gerrard, Mortlock, Rogers, Tuqiri; Larkham, Gregan (capt); Holmes, McIsaac, Shepherdson; Sharpe, Vickerman; Chisholm, Smith, Elsom.
Replacements: Shepherd for Gerrard (66), Rathbone for Rogers (31), Cordingley for Gregan (72), Paul for McIsaac (52), Baxter for Shepherdson (52), Waugh for Smith (70), Palu for Elsom (65).
Ireland: Dempsey; Horgan, B O'Driscoll (capt), D'Arcy, Trimble; O'Gara, Stringer; Horan, Flannery, Hayes; O'Callaghan, O'Connell; N Best, Wallace, Leamy.
Replacements: Murphy for D'Arcy (74), Staunton for Trimble (80), Boss for Stringer (67), Young for Horan (61), R. Best for Flannery (67), M O'Driscoll for N. Best (61), Gleeson for Wallace (70).
Referee: Kelvin Deaker (New Zealand).