Mr Vaki was found not guilty of abusing his office regarding his conduct to instruct a private lawyer to seek a stay of a warrant of arrest issued against Prime Minister O'Neill and Finance Minister James Marape in 2014.
The newspaper, The National, reports Justice David Cannings said he found Mr Vaki's evidence convincing and honest, and that his actions were within his powers as police commissioner.
He said the decision did not prejudice the rights of the investigating officers, Mathew Damaru and Timothy Gitua from the police anti-fraud squad, who have been in open conflict with Mr Vaki over the case surrounding Mr O'Neill.
Mr Vaki said he was delighted with the decision.
However a ruling was still pending in Vaki's Supreme Court appeal against his seperate, contempt of court conviction for preventing police from executing the arrest warrant on the prime minister.
Source: Radio New Zealand