The sentence of a man who covered up a fatal hit-and-run of an Indigenous woman on a Darwin highway in 2022 has been reduced on appeal, allowing him to walk free after 2.5 years in prison.

Joshua Mason, 25, was originally sentenced by the Northern Territory Supreme Court to six years imprisonment with a non-parole period of three years in December 2023, after pleading guilty to hit-and-run causing death, perverting the course of justice, and interfering with a corpse.

In May 2022, Mr Mason struck Anmatyerre woman, known culturally as Kumanjayi Nungarrayai Dixon, while driving whilst suspended on a rural Darwin highway.

During the trial the court heard instead of calling triple-0 for assistance following the collision, Mr Mason called his mother, Deborah Mason, with the pair transporting Ms Dixon's body in the back of a ute before burying it in a shallow grave.

Following the incident, Ms Dixon's body was located in rural Darwin bushland two days after her disembodied leg was found on the side of the Stuart Highway.

Mr Mason appealed the sentence earlier this year.

Heard by the NT Court of Criminal Appeal on Friday, the appeal was upheld based on the sentence being considered manifestly excessive, with Mr Mason, who has served 30 months to date, being re-sentenced to three years, suspended immediately.

The ABC reports that during court submissions prosecutor Lloyd Babb SC labelled Mr Mason's actions "extremely serious" offending, saying his intention was to make Ms Dixon's body "disappear" to "cover up his involvement" in the incident.

"Had the plan succeeded, the deceased would have been a missing person, and the family would never have known what happened to her, and that is extreme criminality in terms of perverting the course of justice," Mr Babb told the court.

Mr Babb said the severity of Mr Mason's offending increased as he failed to contact authorities following the incident, meaning police weren't able to investigate Ms Dixon's death to the best of their ability.

One of three judges presiding over the appeal, Justice John Burns, said there was no doubt Mr Mason's offending was serious, saying "it's just a question of how serious".

"There's no minimum penalty prescribed for these offences, so in theory anything from a non-conviction order up to the maximum is available," Justice Burns said.

Mr Mason's defence barrister, Ian Read SC, told the court the time served in prison by his client "would equate with the minimum term justice requires he serve in custody".

"He's now done a lengthy term and the time he's done is longer than many head sentences for pervert the course [of justice]," Mr Read said, according to the ABC.

Having served 30 months in custody, Mr Read highlighted Mr Mason's "very good work record" and numerous "glowing" character references.

Justice Sonia Brownhill said Mr Mason was entitled to the sentence reduction, acknowledging his guilty plea and remorse for his actions.