Prosecutors said the singer, whose real name is Mark Myrie, told an police informant he could broker the drug.
But Banton testified in court he was merely boasting, and prosecutors conceded he had never put money into a deal, nor made any.
His Before the Dawn won Best Reggae Album at the Grammy awards last week.
On Tuesday, Banton was convicted of conspiracy to possess cocaine with the intent to distribute it, another drug trafficking offence and a gun charge. He was acquitted of a fourth charge for attempted cocaine possession.
He now faces at least 15 years in prison, according to his lawyer, and he is being held for sentencing at a future date.
It was Banton’s second trial over the charges; his first ended in September when a jury was unable to reach a verdict.
Much of the case hinged on video and audio recordings taken by the informant and by Drug Enforcement Agency personnel. The informant was paid $50,000 after Banton’s arrest in December 2009 with two others.
One video shown to the jury showed Banton apparently tasting cocaine in a Florida warehouse.
A co-defendant later gave the informant $135,000 (£83,705). He and another man have pleaded guilty to drug charges in the case.