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 Mr Michel received more than $100m (£80m) from Malaysian billionaire Jho Low that was used in two efforts to influence US politics.
He denied the charges, telling jurors that he thought it was "free money" and he was a "celebrity surrogate".
BBC reports the rapper now faces years in prison.
Mr 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 plans 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 has 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 Mr Michel, is accused of stealing about $4bn from Malaysia's sovereign wealth fund during the infamous 1MDB scandal.
Mr Michel was alleged to have helped lobby Trump-administration officials to abandon their investigation into Mr Low's part in it.
Additionally, Mr Michel was also accused of taking money 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 Mr Michel "was looking for other ways to be paid" after his music career stalled.
She also said that he "saw an opportunity to make money" through Mr Low, who "needed a different type of help" to avoid the consequences of the 1MDB scheme.
While Mr Michel acknowledged taking money from Mr Low - including $20m to help him get a photo with Mr Obama - he said he viewed the payments as "free money".
Taking the stand in his own defence, Mr Michel said he also felt "betrayed" by his advisers and employees, who he claimed offered him bad advice on how to how to handle money and avoid breaking the law.
He acknowledged, however, that it was "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.
Photo Getty Images Caption: Prakazrel "Pras" Michel told jurors he believed the payments were "free money" from a Malaysian tycoon