Irish flyhalf Sam Prendergast slotted the winning conversion to break the deadlock with three minutes remaining after replacement forward Thomas Clarkson forced his way over to crush Australian hearts on Saturday night.
In one last twist, after the lead had changed seven times in the 10-try thriller at Allianz Stadium, Ben Donaldson had the chance to snatch victory for the Wallabies, but pushed a penalty goal attempt wide from more than 40 metres out.
Trying to extend Australia's five-point buffer beyond a converted try, Donaldson also missed a shot from a similar spot moments earlier.
While gutted at falling short of a first victory over the third-ranked Irish since 2018, Wallabies captain Harry Wilson had no regrets about Donaldson going for goal rather than for the line to push for a match-winning try from closer range.
"I backed 'Dono'. I know he's a good kicker and I loved how he stepped up in that moment. He wanted it, and that's what you want from your 10," Wilson said.
"I can live with him missing that because he wasn't scared at the moment and I'm sure down the future he'll step up and get that win for the Wallabies."
Ultimately, the Wallabies once again paid the price for their ill-discipline as Ireland jagged their match winner when the home team were down to 14 men after Test debutant Lachie Shaw was yellow-carded for too many goal-line infringements from the home team.
In a vastly improved showing after enduring a depressingly winless spring tour of Europe last November, the Wallabies otherwise played with aggression and enterprise to threaten to snap a five-match losing streak against Ireland.
"It was one hell of a Test match," said triumphant but relieved Irish coach Andy Farrell.Â
Vindicating his return after a 1316-day Test exile, electric fullback Jock Campbell was Australia's best, while starting debutants Ryan Lonergan and Josh Canham also each scored one of the Wallabies' five tries.
Alas, the visitors had the final say, ultimately condemning Joe Schmidt's side to five consecutive defeats.
The sorry run is the first time the Wallabies have lost that many Tests in a row since the dark days of Eddie Jones' second coming as national coach in 2023.
In a rollicking start to the high-octane encounter, Campbell put winger Dylan Pietsch over for the opening try in just the third minute before doing it all himself for Australia's second.
Cian Prendergast and Josh van der Flier kept Ireland in range with responding tries, with Canham the unfortunate defender on both occasions charged with the impossible talk of stopping the storming flankers from close range.
Canham hit back to restore Australia's lead with a determined pick-and-drive try, before a supporting Lonergan backed up to prosper from an intercept and 35-metre burst from superstar winger Max Jorgensen.
The Wallabies rued conceding a try to British and Irish Lions general Jamison Gibson-Park after the halftime siren, when the Irish pluckily worked their way down field from a scrum 80m out from Australia's line.
Another Irish try quickly after the resumption, when fullback Hugo Keenan had Jorgensen and Joseph-Aukuso Suaalii grasping at thin air, must have had scarred Wallabies fans wondering if this was to be another second-half fade-out.
But a moment of inspiration from livewire half Tate McDermott, on after a knock to the throat forced Lonergan off, turned the tide back Australia's way.
McDermott took a quick tap and beat six Irish defenders to somehow scramble his way over and put the Wallabies back in front, 31-26.
But Ireland had the last laugh, leaving the Wallabies to settle for two consolation bonus points to start the new-look competition - one for scoring four tries or more and one for losing by less than seven points.
9°C