Waylon Ngaketo Cowan Walker was acquitted of murder but found guilty of two counts of manslaughter in March 2021 and sentenced to 12 years' imprisonment.
Cory Breton, 28, and Iuliana Triscaru, 31, were lured to a unit at the Logan suburb of Kingston, tortured, assaulted and bound with tape and zip ties before being put in the toolbox on January 24, 2016.
The box was put onto the back of a ute and dumped in the Scrubby Creek Lagoon, south of Brisbane.
Queensland Court of Appeal Justice Jean Dalton on Tuesday ordered verdicts of acquittal be entered for Walker's two convictions of manslaughter.
Justice Dalton has yet to publish her reasons for allowing Walker's appeal.
Walker's barrister Damian Walsh previously submitted the convictions were unreasonable and could not be supported by evidence.
Mr Walsh's written submission stated Walker's alleged involvement was limited to attending the Kingston unit for an unrelated purpose and he did not interact with the victims.
"Walker was not present at any time during the course of the assaults of both deceased, the binding of the deceased ... and the placing of the toolbox in the lounge room," Mr Walsh stated.
He also said the jury was improperly directed on how to consider Walker's conduct after the killings, including his "lies" to police and travelling to New Zealand, where he is a citizen.
Walker's co-accused Stou Daniels, Davy Malu Junior Taiao and Trent Michael Thrupp were convicted of two counts of murder in 2021 and sentenced to life in prison.
Speaking outside court, Walker's defence solicitor Daniel Hannay said he was happy to have helped clear his client's name and have him released after almost seven years in custody.
"Unfortunately his battle will continue with immigration and his status here in Australia, but he is getting advice in respect to that, but I will continue to assist him where I can with that process, should he wish to continue to reside here in Australia," Mr Hannay said.
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