Sealing the series a match early was some consolation for Michael Clarke's team after they conceded a hard-fought series 1-0 against the top-ranked test nation South Africa with a stinging defeat in the third and final test in Perth.
"I said that at the start of the series that our goal was to win these three test matches and really show that we learnt from the South African series," Clarke, who scored a sparkling 106 at the MCG to cap a brilliant year with the bat, told reporters.
"So far we've done that... My goal doesn't change."
Seamer Mitchell Johnson was justly named man-of-the-match after taking six wickets and making an unbeaten 92 with the bat in an outstanding return to the team after being dumped from the first test victory in Hobart.
Johnson took 4-63 in the first innings to lead the bowling as Sri Lanka were skittled for 156, but his bone-crunching menace may have Australia's selectors pondering a more permanent role for the mercurial paceman.
Johnson broke Prasanna Jayawardene's thumb in the first innings to force the wicketkeeper to surrender the gloves to Kumar Sangakkara, then broke the replacement's left forefinger in the second innings in a fiery bout of short-pitched bowling.
Sangakkara came off the ground immediately after being struck on the glove by Johnson and the Sri Lanka team later confirmed their master batsman would be sidelined for six-to-eight weeks.
"I think that intimidation factor definitely worked out there today," the 31-year-old Johnson said.
Johnson missed out on his second test century as Australia were bowled out for 460 in the morning session, but was immediately consoled by playing a direct hand in the first two wickets of the second innings, as Sri Lanka's top order disintegrated.
The tourists lost three wickets in the first 12 balls to be flailing at 3-3, and another within the next four overs.
A horrible misunderstanding between openers Dimuth Karunaratne and Tillakaratne Dilshan led to the former run out for one on the third ball of the innings.
After smart fielding from David Warner, Johnson lunged to throw down the stumps from point-blank range with Karunaratne well short of his ground following a mix-up between the batsmen over a second run.
Dilshan was gone for a first-ball duck off Johnson's next delivery when he tried to fend off a short ball, only to flick an edge onto his thigh pad that rebounded for a simple catch to Cowan at short leg.
Sri Lanka captain Mahela Jayawardene was heading back to the pavilion for a duck in the next over, shaping to leave the ball but playing onto his stumps to give debutant Jackson Bird his first wicket of the morning.
The 26-year-old seamer struck again in the sixth over of the day, trapping Thilan Samaraweera lbw for one.
Sri Lanka lurched to lunch at 43-4, and after losing Sangakkara, who retired hurt on 27, were quickly despatched.
With seamer Chanaka Welegedara and Jayawardene absent injured, Johnson, fellow paceman Peter Siddle, and spinner Nathan Lyon shared the remaining three wickets.
Angelo Mathews battled hard to top-score for Sri Lanka with 35, but was out playing onto the stumps off the bowling of Johnson when attempting a hook that rebounded onto the stumps.
Dhammika Prasad struck two successive sixes off Lyon but was caught at cover by Phillip Hughes for 17 on the next ball.
Siddle clinched the winning wicket by having Shaminda Eranga caught for a duck.
Sri Lanka captain Mahela Jayawardene said blame would be shared throughout the team for handing Australia their seventh most dominant innings victory in tests.
"Today the performance was very disappointing with the boys," he said. "We need to show more character, we need to see more from the players, especially when you're playing a team like Australia."