The president wrote on Twitter: “It is my Great Honor to announce that General Michael T. Flynn has been granted a Full Pardon.”
“Congratulations to @GenFlynn and his wonderful family, I know you will now have a truly fantastic Thanksgiving!” he continued.
Mr Trump fired General Flynn in 2017, just 24 days into his presidency, for lying to Vice President Mike Pence and the FBI about conversations he had with Russia’s ambassador.
Mr Flynn, the Trump presidency’s first national security adviser, twice pleaded guilty to lying to federal investigators. This also included lying about illegally lobbying for the government of Turkey.
Many of the Trump administration’s problems can be traced back to Flynn, as his dismissal led to the president asking James Comey not to prosecute him, which led to his firing, and the appointment of Robert Mueller.
Mr Trump has spoken before about pardoning Mr Flynn. In March he said he was strongly considering it.
While the president is insisting publicly that the election is not yet over and the he really won — and as recently as this afternoon spent ten minutes decrying voter fraud over the phone to a GOP hearing in Pennsylvania — this is likely a sign he realises that his days in the White House are numbered.
Sources have told ABC News that this could be the beginning of a pattern over the next few weeks.
Rather than announcing a number of pardons all at once when he leaves office, Mr Trump knows he will get more attention by sprinkling pardons as and when he sees fit.
Ever the showman, this means he will continue to get attention in the last days of his presidency — and a final load of pardons is not out of the question.
House judiciary committee chairman Jerry Nadler released a statement: “This pardon is undeserved, unprincipled, and one more stain on President Trump’s rapidly diminishing legacy.”
Representative Adam Schiff remarked: "It's no surprise that Trump would go out just as he came in – crooked to the end."
Mr Nadler adds that it is important to talk about why the president pardoned Mr Flynn.
“President Trump dangled this pardon to encourage Flynn to backtrack on his pledge to cooperate with federal investigators — cooperation that might have exposed the president’s own wrongdoing. And it worked," said Mr Nadler.
“This pardon is part of a pattern. We saw it before, in the Roger Stone case … We may see it again before President Trump finally leaves office," he added.
The news also comes just a day after the president partook in the annual tradition of pardoning the White House turkey, Corn.
At that event a reporter shouted out asking if Mr Trump would pardon himself before he left office. The president did not answer and retreated into the executive mansion.