A New York jury found that Mark Scott helped to perpetrate the scheme, routing approximately $400m (£310m) out of the US while working to conceal the true ownership and source of the funds.
Prosecutors said he made about $50m.
Mr Scott's lawyers had said he did not know that OneCoin was worthless.
They said he was simply doing the job asked by Dr Ruja Ignatova, a co-founder of the Bulgaria-based OneCoin.
The federal jury in Manhattan rejected those arguments, finding Mr Scott guilty of conspiracy to commit money laundering and bank fraud.