Australia recovered from conceding a first-minute try and twice falling 10 points behind to beat Wales 30-26 in Cardiff.
The Wallabies scored three tries to two from Wales wing George North, with Australia centre Christian Leali'ifano, who crossed the Welsh line, contributing 20 points in all.
This success for Ewen McKenzie's men was all the more significant given Australia and Wales have been drawn in the same World Cup 'group of death' as 2015 hosts England.
The Wallabies' tour-ending triumph also meant they'd won four Tests in a row for the first time since the opening matches of former coach Robbie Deans's reign in 2008.
The match marked Wallabies first five Quade Cooper's 50th test.
For Six Nations champions Wales this loss extended their poor run against the southern hemisphere sides of New Zealand, South Africa and Australia to just one win in 23 Tests.