He apologised for his actions, telling a judge that he had made a "dreadful mistake" and was eager for redemption.
Prosecutors working for special counsel Robert S Mueller III had asked the judge to sentence Papadopoulos to six months in prison, saying his false statements "were meant to harm the investigation, and did so". Despite constant attacks by the president, Mueller and his team "are conducting a serious, professional investigation" into the 2016 Trump campaign's contacts with Russians, Warner said in a statement.
Thus began the FBI's counterintelligence investigation into Russia's election interference operation, American officials have confirmed - an investigation that was taken over by Mueller in May 2017.
He admitted past year to lying to the FBI about those contacts with Russians and Russian intermediaries, false statements that prosecutors say caused irreparable harm to the investigation during its early months.
He said Mr Trump had hampered the inquiry by calling it a "witch hunt" and "fake news".
In addition, they said Papadopoulos did not provide "substantial assistance" and only came clean after he was confronted with his own emails, texts and other evidence.
Outside court on Friday, Papadopoulos' lawyer, Thomas Breen, said his client was a "fool" and had acted "stupidly" by lying to the Federal Bureau of Investigation. "I saw him sitting in one picture at a table with me - that's the only thing I know about him", he said, an apparent reference to a March 31, 2016, campaign meeting that Papadopoulos and Trump attended.
They said Papadopoulos' initial lies hindered investigators' ability to effectively question, challenge or detain Joseph Mifsud, the London professor who had contacted him.
"It wasn't an offer", he said Friday night, denying that Mifsud had dangled the possibility of funneling the emails to the Trump campaign.
His lawyer Tom Breen said that at the time, Papadopoulos was naive and acted on what he told the court was a "misguided loyalty" to Trump, who had been inaugurated as president just one week before.
At that meeting, Mr. Papadopoulos proposed brokering a meeting between Mr. Trump and Russian President Vladimir Putin.
"14 days for $28 MILLION - $2 MILLION a day, No Collusion".
Prosecutors said the lies Papadopoulos told slowed the investigation and prevented the FBI from arresting Mifsud before he could leave the United States. "A great day for America!" he said, unsuprisingly, in a Tweet.
Papadopoulos said even his family was concerned about his romantic relationship and suspected his wife was a Russian spy.
For a time, Papadopoulos also looked to be a key informant.
With the sentence, the young man whom Trump administration officials called a "coffee boy" and whose family members have argued is caught in a spy conspiracy will become the first Trump campaign affiliate to have his criminal case reach its completion in the court system.