Ex-Fugees musician Prakazrel "Pras" Michel has been found guilty of 10 counts, including corruption, stemming from allegations he used money to peddle influence in the US.
US prosecutors said Michel had received more than $100m (£80m) from Malaysian billionaire Jho Low that was used in two efforts to influence US politics.
The self-identifying "celebrity surrogate" was also convicted of lobbying on behalf of China's government.
The rapper now faces years in prison.
Michel, 50, was convicted in a Washington DC court of campaign finance violations, acting as an unregistered foreign agent, witness tampering and lying to banks.
His lawyer, David Kenner, said that he was disappointed with the outcome of the trial and planned to file an appeal.
"This is not over," Mr Kenner said. "I remain very, very confident that we will ultimately prevail in this matter."
Mr Kenner said he had also filed motions for a mistrial.
The trial, which began on 30 March, saw testimony from Hollywood star Leonardo DiCaprio, as well as former US Attorney General Jeff Sessions.
The Grammy-winning musician was accused of bringing "secret, illegal, foreign influence to bear" during the administrations of Barack Obama and Donald Trump, between 2012 and 2017.
Businessman Mr Low, who funnelled money to Michel, is accused of stealing about $4bn from Malaysia's sovereign wealth fund during the infamous 1MDB scandal.
Mr Low, who is currently wanted by the US government, allegedly helped finance DiCaprio's 2013 film The Wolf of Wall Street with money stolen from the sovereign fund.
Michel was alleged to have helped lobby Trump-administration officials to abandon their investigation into Mr Low's part in it.
Additionally, Michel was also accused of taking money from China to lobby US officials to extradite a US-based dissident, Guo Wengui, back to China.
The government's lead prosecutor, Nicole Lockhart, told jurors that Michel had been "looking for other ways to be paid" after his music career stalled.
She also said he had seen an "opportunity to make money" through Mr Low, who "needed a different type of help" to avoid the consequences of the 1MDB scheme.
While Michel acknowledged taking money from Mr Low - including $20m to help him get a photo with Mr Obama - he said he had viewed the payments as "free money".
Taking the stand in his own defence, Michel said he also felt "betrayed" by his advisers and employees who he claimed had offered him bad advice on how to handle money and avoid breaking the law.
He acknowledged, however, that it had been "stupid" to reach out to "friends" who were "getting visits" from the FBI about campaign contributions - an idea that led to his witness tampering charges.