The Supreme Court of Appeal set aside the conviction and 28-year sentence imposed on Msobomvu Qhinga, after the Bhisho High Court sent him to jail along with five accomplices.
Without giving details, the judgment also freed Camagu Zimela and Luvuyo Mmcaphukisi.
The convictions and sentences of Lungile Jamiso, Lizo Lumbe and Lindile Magi were not set aside.
The men were arrested in 2006 following a heist in which social grant money was stolen.
A group of men dramatically stormed the precinct of a community hall in Newlands, near East London, and fled with the money.
A security guard was shot and injured before being robbed of his firearm with 18 rounds, while his colleague was robbed of his firearm and 30 rounds. To get away, the group hijacked a car and later fired shots at a policeman.
The Bhisho High Court found the six guilty on four counts of robbery with aggravating circumstances and two counts of attempted murder. It sentenced five to an effective 28 years' imprisonment, while one was sentenced to 22 years.
Qhinga, who was accused number one in court, has been appealing against his sentencing and conviction since 2009. His breakthrough came eight years later.
The 54-year-old father of two, who has been in jail since his arrest in 2006, has been arguing that he pointed out the suspects at the behest of the police, which was incorrectly admitted as evidence in court.
The pointing out of the accomplices, which amounted to a self-incriminating confession, was the State’s main evidence in court as the robbers had not been identified.
One Superintendent Sonwabile Nkosiyana apparently testified about the pointing out of the accomplices. But the SCA found no records indicating that Nkosiyana had testified and whether the pointing out of the accused was declared admissible evidence by the court.
“The result is that either Nkosiyana never gave evidence to prove the content of the pointing out of the accomplices or his evidence is lost and cannot be reconstructed,” the SCA judges found.
“There is no evidence whatsoever implicating the appellant in the commission of the offences."