A jury at London's High Court ruled on Monday that Diana and her lover Dodi al-Fayed were "unlawfully killed" by the "grossly negligent" driving of chauffeur Henri Paul in Paris on August 31, 2007.
Lord Justice Scott Baker said there was "not a shred of evidence" to support al-Fayed's allegation that Queen Elizabeth's husband Prince Philip, Diana's former father-in-law, had ordered British security services to kill her and stop her marrying a Muslim and having his baby.
Al-Fayed said in a statement after the verdict: "I'm not the only person who said they were murdered.
"Diana predicted that she would be murdered and how it would happen, so I am disappointed."
He insisted that the queen and her husband should have been called as witnesses.
He said: "No one should be above the law. I have always believed that Prince Philip and the queen hold valuable evidence that only they know."
Diana's sons, Princes William and Harry, welcomed the verdict.
The pair said in a statment: "We should like to thank the members of the jury at the inquests into the deaths of our mother and Dodi al Fayed for the thorough way in which they have considered the evidence.
"We agree with their verdicts, and are both hugely grateful to each and every one of them for the forbearance they have shown in accepting such significant disruption to their lives over the past six months."
Over 250 witnesses from around the world testified at the $20m inquest, which began almost six months ago.