The Appeal Court delivered the unanimous decision a short while ago via teleconferencing.
Vybz Kartel, whose real name is Adidja Palmer, and co-accused Shawn 'Shawn Storm' Campbell, Kahira Jones, and Andre St. John, were convicted in 2014 for the 2011 murder of Clive 'Lizard' Williams.
Justice Lennox Campbell gave Kartel and his co-accused mandatory life sentences for murder.
The artiste was ordered to serve 35 years before becoming eligible for parole, while Campbell, Jones and St. John were each ordered to serve 25 years.
Kartel and his co-accused had been waiting almost two years on the ruling following their three-week appeal hearing in July 2018.
Their legal team had filed 14 grounds of appeal.
The lawyers have indicated they will challenge the decision at the Privy Council.