But the court win for Hicks, who has been in US custody at Guantanamo Bay for four years, is not the end of the legal wrangling over his bid to become a British citizen.
Britain's Home Office is expected to launch a further appeal, after its bid in the Court of Appeal failed.
The home office has until April 25 to seek a further appeal to the House of Lords, which acts as Britain's highest court.
The Court of Appeal will rule on any such application by early May.
If it is denied, the home office has the further option of petitioning the House of Lords directly.
There is currently a stay on Hicks being registered as a British citizen, pending a possible further appeal.
Meanwhile, US authorities at Guantanamo Bay have placed Hicks in solitary confinement.
His US military lawyer Michael Mori and civilian lawyer said they have only recently learned of his return to isolation, and no reason was given for the decision.
The lawyers said the confinement is to break his will and punish him, regardless of whether he his ever found guilty on terrorism-related offences.
"The information I'm getting is David has done nothing to motivate this," Major Mori told reporters in Adelaide.
"It was just some decision randomly made or made with some ill motive.
"I don't know what the motivation was but I'm sure if he's stuck back in isolation it will break his will."
Hicks spent 16 months in solitary confinement at Guantanamo in 2003 and 2004, including eight months with no access to sunlight.
"I intend to go to Guantanamo in the next few weeks and investigate and see what comes out of that visit," said Major Mori.
Hicks' military commission trial is currently on hold, pending the decision of a related US Supreme Court matter involving another terrorism suspect.
Hicks hopes that if he becomes a British citizen, the UK would lobby for his release, as it has for other British subjects held at the camp in Cuba.
The Australian government, in contrast, has made no effort to free Hicks, leaving his fate in the hands of the US military commission process.