But they found him guilty on a charge of manslaughter.
There were gasps from the public gallery when the verdicts were returned.
Justice Rob Osborne gave him a three-strike warning and remanded him in custody to be sentenced on February 10.
The court earlier heard how Heappey, known as "Smiley", had ignored repeated requests to settle a $300 debt and turn over a stolen Subaru car to the Nomads' Christchurch chapter president's daughter.
Burke admitted knowing the gang's plan to give Heappey a hiding.
But he claimed he didn't know that 31-year-old gangland enforcer Matthew Winara Webber had a knife and that he was going to stab him.
After the attack, Heappey was bundled into a car and driven to Christchurch Hospital where he would soon die from his injuries.
Heappey knew he'd done wrong by the gang and was waiting to receive his punishment on December 8, 2018.
He owed $300 for a drug debt to Leone Sherie Cook – the 28-year-old stepdaughter of Nomads Christchurch chapter president Randall Clinton Waho.
She also wanted a stolen car that Heappey had been driving around in handed over to her and asked her stepfather to get involved.
Waho, 47, set up several meetings with Heappey, the court heard, but he never showed up.
That was a slight against the gang and its president, the Crown said.
The Crown said Burke had only been in town for a month but had started a relationship with Cook and was aspiring to join the Nomads and become a patched member.
Cellphone records and text data shows the gang wanted to put Heappey in his place and Waho had allegedly ordered a hiding – and Heappey knew it.
But defence counsel Stephanie Grieve said Burke was as surprised as anyone that Webber "went completely over the top" and beyond the gang's plan to give Heappey a beating for some minor gang infringements.
"Mr Burke is not guilty of murder," she told the jury.
"Mr Burke had no idea that Mr Webber would stab Mr Heappey. He didn't know he had brought a knife."
Grieve said that even in a gang like the Nomads, there was common sense and logic.
"People don't get killed over $300 and a car," she said.
Webber, Waho, Cook, and another gang member, Richard John Sim, 52, who had been tasked with tracking Heappey, have already been convicted over Heappey's death.