David Hicks, who spent five years in the US detention camp in Cuba, said he had not yet decided whether to seek broader compensation in Australia.
"I do think that someone should be responsible for my medical expenses," Hicks told reporters in Sydney.
"I was subjected to five-and-a-half years of physical and psychological torture that I will now live with always."
Hicks pleaded guilty in 2007 to providing material support to terrorism but on Wednesday the US Court of Military Commissions Review threw out his conviction because such activity did not become a crime until years after he was captured in Afghanistan, Reuters reported.
Hicks was among the first group of prisoners sent to Guantanamo when the detention camp in Cuba opened on Jan. 11, 2002. He had acknowledged he had trained at an al Qaeda camp in Afghanistan and met the Islamist group's leader Osama bin Laden.
His lawyers have said Hicks was innocent and that he made the guilty plea under duress after enduring years of beatings, sexual assaults and sleep deprivation.
The ruling by the US military appeals court stressed that the decision to vacate his conviction was made on technical grounds. The judgment said Hicks was captured by members of the Northern Alliance fighting the Taliban and handed over to US troops in Afghanistan. It said he had planned to join the fight against the US-backed coalition that ousted the Taliban.
Hicks had joined Lashkar-e-Taiba, a group later designated as a terrorist organization by the United States, in Pakistan. He received weapons training there before traveling to Afghanistan, the three-judge panel said.
Australian Prime Minister Tony Abbott said there would be no apology from the government, which did not challenge Hicks' detention at the US naval base in Cuba.