"The defense rests," Manafort's lead attorney Kevin Downing said in court on Tuesday.
Downing explained the decision to reporters when the court was in recess.
"Mr. Manafort just rested his case," Downing said, "and he did so because he and his legal team believe that the government has not met its burden of proof."
Manafort, who has pleaded not guilty to all charges, is facing a potential life sentence if he is convicted on 18 counts of financial charges, including money laundering and tax fraud.
Government prosecutors from Special Counsel Robert Mueller's office rested their case on Monday after more than two weeks of testimony alleging he hid millions of dollars in offshore accounts and failed to pay taxes on that money.
The case against Manafort has barely referenced his work as President Trump's campaign chairman and has not indicated if he may fit into the larger picture of Russian meddling in the 2016 campaign that Mueller's team is investigating.