The government tried in vain to reverse the Parole Authority's decision that he should be freed, claiming it made errors including that it didn't believe the 33-year-old held radical beliefs.

Elomar emerged from the prison gates on Thursday afternoon just hours after a NSW Supreme Court judge upheld the parole decision.

Elomar was immediately met by a media scrum but did not answer any questions or offer any comment.

Dressed in a grey sweater and tracksuit pants, he clutched a book and a plastic bag of personal effects as he wandered around for at least 10 minutes waiting for a lift.

He was eventually collected about 1km away, where he jumped into a white four-wheel drive which sped off.

NSW Corrections Minister David Elliott said he was bitterly disappointed by the court's decision to free Elomar.

"I do not support the release of an offender to the community from the secure environment of the correctional system where, in my view, that offender remains untreated and continues to threaten the safety of the community," he said in a statement.

The authority said if Elomar remained in custody he would be influenced by others who held radical beliefs and the community would be better served if he was removed from their influence.

In the Supreme Court on Thursday, Justice Geoffrey Bellew dismissed all grounds of appeal and ordered the government to pay Elomar's legal costs.

He was granted parole in July after serving three years of his maximum four-year and eight-month sentence for bashing a police officer with a flagpole during the 2012 riots at Sydney's Hyde Park.

The judge rejected claims that the authority had ignored relevant material including police concerns that the community would be at significant risk if Elomar was released.

Police also contended he had "radical beliefs", submitting he was part of a group of Muslim inmates who administered sharia law at Goulburn jail and had been in the vicinity of a conversation in relation to beheading a person.

They also said he had photographs of his brother, Mohamed Elomar, who was killed in June 2015 while fighting for Islamic State in Syria and regarded him as a martyr.

The judge found the authority was not inaccurate in describing the material as "assertions"."

Further, he found the Authority's conclusion that if (Elomar) remained in custody he might be influenced by inmates who had radical beliefs was a logical one.

He noted that Elomar would live with family members at an address that had been assessed as suitable, would be subject to regular supervision and would resume employment.

The judge said no assessment had ever been undertaken as to whether Elomar was at risk of radicalisation or had been identified as having already been radicalised.