The victory, sealed before lunch on the fourth day, gave holders England a 2-1 lead in the series, which will be completed with the fifth and final Test in Sydney [ Images ] next week.
Australia [ Images ] resumed on 169-6, still facing a 246-run deficit to make England bat again but lost their remaining wickets shortly before lunch to be all out for 258.
Chris Tremlett removed Mitchell Johnson [ Images ] for six in the second over of the morning, pushing half-heartedly at a fuller delivery that took an inside edge before crashing into off-stump.
The injured Ryan Harris did not take his place leaving Ben Hilfenhaus [ Images ] to take the crease. The paceman was out to Tim Bresnan [ Images ] for a duck, caught behind to wicketkeeper Matt Prior [ Images ] to complete the innings.
Andrew Strauss's [ Images ] team became the first to retain the Ashes in Australia since Mike Gatting lead the tourists to a 2-1 series win in 1986/87, the decisive victory also sealed at the MCG.