Since that time, the former campaign aide has been cooperating with investigators working with Robert Mueller on the Russian election interference probe.
"I made a awful mistake", Papadopoulos said a courtroom statement.
In requesting that Papadopoulos serve some prison time, government lawyers said he and his wife had participated in media interviews riddled with misstatements.
He has testified that senior campaign members encouraged him during 2016 to build ties with Russian Federation, including after he told them that Moscow possessed - and could be willing to share - dirt on Trump's election rival Hillary Clinton.
US District Judge Randolph Moss said he "lied in an investigation that was important to national security".
The judge said he took into consideration Papadopoulos's "genuine remorse" in issuing the light sentence, which included a $9,500 fine, a year on parole and community service.
Today in court, his lawyers argued President Trump's attacks on the Mueller's investigation have done much more damage to the probe than "George Papadopoulos ever could".
"It was at best begrudging efforts to cooperate and we don't think they were substantial or significant in any regard", he said.
One individual was a Russian woman who Papadopoulos believed had connections to the Russian government.
Papadopoulos, who was initially interrogated on January 27, 2017 by Federal Bureau of Investigation agents regarding his work for the Trump campaign, was arrested at Washington-Dulles International Airport on July 27, 2017 and arraigned the following day.
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". 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. They said prosecutors have not provided any proof that Papadopoulos "actually harmed the investigation as alleged".
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.
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. Last November, Mr Sessions testified to Congress that he had "pushed back" against Papadopoulos' offer.