David Campbell, 53, and Tristan Waters, 40, were arrested in January 2018 after a meeting with undercover operatives at a luxury hotel in Belgrade, along with a third Australian, Rohan Arnold, who they were accused of conspiring with.
Authorities had allegedly found almost a tonne of pure cocaine, worth more than a billion dollars, concealed in steel beams from China inside a shipping container at Sydney's Port Botany the previous year.
The arrests and eventual extraditions came at the end of a globe-trotting undercover police operation where officers posed as criminals who had happened upon a missing shipping container filled with cocaine, eventually luring Campbell to New Zealand to retrieve it.
Waters had pleaded guilty in the NSW District Court to conspiring to possess the illicit drugs but denied any involvement in its importation.
On Tuesday, the jury found him not guilty of conspiring to import.
Campbell had pleaded not guilty to both counts but the jury found him guilty of attempted cocaine possession.
The 53-year-old previously told the court he only participated under duress due to threats to his family.
While the prosecution alleged Waters was a high-ranking principal figure in a drug syndicate, his lawyers argued otherwise.
They claimed he was an outside troubleshooter brought in to play the role of a "heavy" and act as a principal.
A jury of six women and six men retired for about two weeks before coming to their decisions.
The duo will be sentenced on October 19.
