The Wallaby fly-half dived over in the right-hand corner after Dave Dennis' burst just as it looked as though Wales would finally end a six-match losing streak.
Wales were good value for their 12-9 lead thanks to four Leigh Halfpenny penalties but they couldn't hold on for what would have been a first win over the Wallabies in six attempts in the past 13 months.
Having experienced heartbreak in Brisbane, Melbourne and Sydney in June of this year, Warren Gatland's men were once again on the wrong end of the late drama despite having produced their best display of their autumn.
Gatland admitted afterwards that you 'couldn't write the script' but the man charged with leading the Lions Down Under in 2013 will hope for a kinder story with Britain and Ireland's elite.
Australia led 9-6 at the break after Beale kicked three penalties compared to two from Halfpenny in an evenly contested opening 40 minutes but Wales were the better side in the second period.
Wales created the better scoring chances in both halves and were the more willing to run the ball from deep but they couldn't quite conjour up a try in Cardiff.
Halfpenny's brilliant attacking line almost resulted in that elusive score with 25 minutes gone but Wyclif Palu just beat Sam Warburton and Toby Faletau to the loose ball after the full back chipped ahead having raced from one 22 to the other.
Australia's best attacking moment prior to Beale's late, late intervention came when Adam Ashley-Cooper's forward pass butchered a two-on-one deep in Welsh territory but they didn't offer as much threat out wide as they'd have liked.
Halfpenny had Wales ahead on the hour mark and they looked largely in control of their own fate despite failing to get across the Wallaby line.
But all that changed in the closing moments as Australia attacked from deep, kept ball in hand and broke through the Welsh defence on a number of occasions.
Wales looked to have stopped the threat and sealed the win after turnover ball allowed Rhys Priestland to kick downfield when Berrick Barnes was brought down after a mazy run deep into Welsh territory.
But the Wallabies somehow created one final chance as things got loose, with Beale and Dennis combining to show just how clinical the Lions' next opponents can be.
And if defeat in such frustrating circumstances wasn't enough for Wales to contend with, Halfpenny's departure on a stretcher seconds before the final whistle added injury to insult.
The 2009 Lion looked in serious discomfort as he was carried off wearing an oxygen mask following a heavy knock in the build up to Beale's try.