The decision upends an agreement that Manafort, Trump's former campaign chairman, had struck with prosecutors before pleading guilty to conspiracy and obstruction of justice, and now means he faces a longer prison sentence.
U.S. District Judge Amy Berman Jackson said in an order Wednesday that Manafort "intentionally made false statements" to the FBI and to prosecutors about his interactions with a Russian associate and other subjects.
Mueller sought to void the plea agreement in November after prosecutors alleged that Manafort had misled them about his interactions with a Russian business associate, his contacts with Trump's administration and other subjects. Manafort's lawyers mistakenly revealed that one of the lies he was accused of telling related to his sending polling data to a Russian associate during Trump's campaign.