The Pacific Islanders, forced to play as Tonga Invitational XIII due to political infighting, beat the Lions 14-6 in Hamilton last month before pulling off a stunning 16-12 defeat of the world champions at Eden Park on Saturday.
New Zealand, Great Britain and England were the only sides to have beaten Australia in the previous 41 years before their stunning loss to Kristian Woolf's side.
The Tongan team have been invited for an official reception in recognition of their victories and they will be even more popular after a national holiday was declared.
Prime Minister Pohiva Tu'i'onetoa said in a statement: "Such is the spirit of immense joy, felicitations and thankfulness conveyed, on behalf of His Majesty The King Tupou VI, the Government and the people of the Kingdom of Tonga.
"To the captain, the manager, the officials and the head coach of the Winning Warriors Tonga team respectively, for the outstanding, awe inspiring and unique triumph of the Tonga Rugby League Invitational XIII over the reigning Australian and British rugby league Teams."
Photo Getty Images Caption: Tonga celebrate beating Australia