The 28-year-old defence journalist died while investigating the sale of attack helicopters to Saddam Hussein's Iraqi regime.
The verdict was returned by the Exeter and East Devon coroner after a two-hour hearing at Exmouth Coroner's Court.
Afterwards, Mr Moyle's family, who have never stopped investigating the circumstances surrounding his death, said that some justice had been done.
His mother Diana said: "It would have been so immensely unfair if any other verdict had been returned. It has been a long time, eight years, and it has been hanging over us every day. I just feel relieved."
When the body of the former RAF helicopter pilot was discovered hanging in a 5ft high wardrobe in a Santiago hotel room, the Chilean authorities said he had committed suicide.
Eight months later, an inquest was opened near Mr Moyle's home in Devon. But the coroner was forced to adjourn the hearing after a pathologist said that vital body organs were missing.
The inquest was finally reopened yesterday after further investigations by the authorities in Chile and by Mr Moyle's father Tony. A retired schoolteacher, Mr Moyle became convinced that his son was killed after being given a sedative in his coffee.
When the body was discovered on 31 March, 1990, the Foreign Office at first accepted the Chilean authorities' view that he had committed suicide.
But it later emerged that Mr Moyle had been working on a story that Carlos Cardoen, a wealthy Chilean arms dealer, had brokered a deal to supply Iraq with helicopters equipped with guided missiles. Mr Cardoen had earned millions from Iraq's protracted war with Iran and was also linked to the deals by which British engineering company Matrix Churchill supplied lathes to manufacture Iraqi ammunitions.
Mr Moyle had arrived in Santiago as a delegate at an international defence conference.
He began investigating claims that Mr Cardoen was preparing to convert the Bell 206 civilian helicopter into an attack aircraft carrying a guided missile system, which was jointly manufactured in Britain, Sweden and the US.
Mr Moyle senior has since spent pounds 10,000 investigating his son's death. His concerns helped prompt a re-think by the Chilean authorities and a judicial investigation in Santiago in September 1991 concluded that the young Briton had been murdered and that his killers had faked his suicide. Two years later, when an identity parade in Chile failed to identify a suspect, the murder hunt was halted.
But the investigation into his death was re-opened by the Santiago Court of Appeal late last year.
Nearly eight years on and just as Britain has narrowly avoided going back to war with Iraq, the Moyle family finally feels that the authorities have done them some justice.