A lawyer for Santos told the Associated Press that it remains unclear when his client would be released.
“The defence team applauds President Trump for doing the right thing,” said Andrew Mancilla.
“The sentence was far too long.”
Santos’s downfall began after the New York Times in 2022 published an investigation revealing the freshman congressman had lied about his CV, including having a university degree and working for Citigroup and Goldman Sachs.
From there, the lies continued to pile up, including allegations that he stole money from a fundraiser for a dying dog and that he lied about his mother surviving the 9/11 terrorist attacks. Shortly afterwards, local and federal officials began to investigate.
He was eventually charged with 23 federal felony crimes, and in 2023 he became the first expelled member of Congress in more than 20 years, and only the sixth in history.
A report from the House ethics panel accused him of misusing campaign funds for personal benefits, including Botox and subscriptions on the OnlyFans website.
Santos defeated a Democratic incumbent in 2022, flipping the district that encompasses parts of New York’s Long Island and Queens, where he grew up.
Earlier this week, Santos published an open letter to Trump in the South Shore Press newspaper in Long Island, repeating his plea to be pardoned.
The letter, which was titled a “passionate plea to President Trump” asked for “the opportunity to return to my family, my friends, and my community.”
He wrote that he had been kept in solitary confinement after a death threat in August, and apologised for his actions.
“Mr President, I am not asking for sympathy. I am asking for fairness – for the chance to rebuild,” he wrote.
“I know I have made mistakes in my past. I have faced my share of consequences, and I take full responsibility for my actions.
“But no man, no matter his flaws, deserves to be lost in the system, forgotten and unseen, enduring punishment far beyond what justice requires.”
Trump has issued pardons to at least two other former Republican lawmakers since re-taking office in January.
In May, he pardoned former congressman Michael Grimm, who pleaded guilty in 2014 to tax crimes.
He also pardoned former Connecticut Governor John Rowland, who pleaded guilty in 2004 to corruption and fraud charges.