His case was the first to detail a member of the Trump campaign having knowledge of Russian efforts to interfere in the 2016 presidential election while it was ongoing.
He was handed a 14-day jail term as he told a court in Washington: "In January 2017, I made a awful mistake for which I paid dearly, I am ashamed".
Papadopoulos was once described as a "coffee boy" to the Trump campaign.
Papdopoulos's lawyer Tom Breen said "the president of the United States hindered this investigation more than George Papadopoulos ever did".
"Judge said he believed Papadopoulos was genuinely remorseful but didn't agree to a probation sentence because he needed to send a message about the seriousness of lying to the FBI", Cheney wrote in a subsequent tweet.
When the Federal Bureau of Investigation interviewed him in January, Papadopoulos falsely claimed he had met two individuals with Russian ties before he joined the president's team in March 2016.
Mr. Papadopoulos was pictured in March, 2016, sitting at a table with Mr. Trump, then-campaign adviser Jeff Sessions who went on to become U.S. Attorney-Ggeneral, and other foreign policy campaign advisers. Mifsud left the United States and not returned, after the Federal Bureau of Investigation found him in the USA on February 11, 2017, about two weeks after Papadopoulos's first interview. Although Papadopoulos confirmed that Mifsud told him Russians had "thousands of emails" involving Clinton, he claimed he hadn't yet joined the Trump campaign when they spoke.
"My entire life has been turned upside down, I hope to have a second chance to redeem myself", he said. In a court filing August 31, Papadopoulos's lawyers painted him as a political newcomer "eager to show his value to the campaign", and quickly got in over his head. "I can't guarantee. All I can say is, my memory is telling me that I never shared it with anyone on the campaign".
While this chapter of the Mueller investigation concludes for Papadopoulos, his testimony and information he provided as part of his plea deal could mean trouble for others in Trump's circle, including Mr. Trump himself.
Papadopoulos's main role in the campaign appears to have been a middleman for invitations from Russian operatives for Trump to visit Moscow and possibly meet with President Vladimir Putin.
Prosecutors said the lies Papadopoulos told slowed the investigation and prevented the FBI from arresting Mifsud before he could leave the United States.
When Papadopoulospleaded guilty past year, he pledged to help the special counsel's office with its investigation.
"Caught off-guard by an impromptu interrogation, Mr Papadopoulos misled investigators to save his professional aspirations and preserve a perhaps misguided loyalty to his master", the statement said.