The Wallabies conceded two tries in the first four minutes and were 31-7 down at half time but after coach Michael Cheika launched a blistering team talk they came out and dominated the second period to hammer a hapless home side.
Izack Rodda, Israel Folau and Dane Haylett-Petty scored tries within 10 minutes of the restart before David Pocock crossed and Haylett-Petty grabbed his second with 15 minutes remaining to make the score 42-34.
Bernard Foley scored a penalty six minutes from time to add to his six conversions and although Tolu Latu got a yellow card for a reckless elbow with four minutes remaining the Pumas could not make their advantage count.
Argentina, who needed a win or a draw to condemn the visitors to last place in the championship, looked shell shocked and could manage only a penalty after the break.
It was the biggest comeback in Rugby Championship history and the largest amongst Tier One nations. Chile held a 27-0 lead at halftime before losing 35-34 to Uruguay in 2007.
The result means the Wallabies leapfrog Argentina to finish third in the final table, behind South Africa and winners New Zealand.
(Reporting by Ramiro Scandolo, Writing by Andrew Downie; Editing by Greg Stutchbury)
