His sentencing came as part of special counsel Robert S. Mueller III's probe that has led to the indictments or convictions of 32 people.
He was also the first to detail a member of the Trump campaign having knowledge of the Russian efforts to meddle while it was going on.
The sentence was imposed in federal court in Washington.
Papadopoulos, who was a foreign policy advisor to Mr Trump, relayed to the then Republican presidential candidate that he had been told by a Maltese academic, Joseph Mifsud, that he had "dirt" on rival Hilary Clinton.
President Donald Trump and his allies have repeatedly downplayed Papadopoulos' role on the campaign.
Also in court, his lawyer, Thomas Breen, criticized Mr. Trump for calling the Russian Federation probe fake news and a witch hunt.
Mueller's team had pushed for a six-month prison sentence, while Papadopoulos' defense had requested probation.
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.
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Papadopoulos was pictured in March 2016 sitting at a table with Trump, then-campaign adviser Jeff Sessions who went on to become USA attorney general, and other foreign policy campaign advisers.
The FBI canceled the meeting when it discovered that Papadopoulos had sat down for a media interview about the case. Papadopoulos had initially claimed this was before he joined the campaign, though he later confirmed it was once he was on staff. In late April, he told them that Mifsud said the Russians had information that could harm Clinton, in the form of thousands of emails.
"As far as I remember, I absolutely did not share this information with anyone on the campaign", Papadopoulos told Tapper.
His mother said on Friday that she "still supports" Trump.
In his pre-sentencing statement, Papadopoulos admitted lying to FBI investigators in January 2017 but said it had been out of a desire to protect his career and a naive loyalty to the Trump administration.
The FBI met with Mifsud while he was visiting the United States in early 2017, but Papadopoulos' lies "undermined investigators' ability to challenge the professor or potentially detain or arrest him".
Papadopoulos obtained a plea deal at the time, which was subsequently unsealed last October.
"Papadopoulos misled investigators to save his professional aspirations and preserve a perhaps misguided loyalty to his master", the lawyers wrote.