The president said he intended to nominate Rep. John Ratcliffe, R-Texas, to replace Coats and would name an acting director in the interim.
"A former U.S. Attorney, John will lead and inspire greatness for the Country he loves," Trump wrote.
The departure was first reported by Axios and The New York Times. Multiple sources had confirmed Coats' departure and Ratcliffe's likely nomination to ABC News.
The Office of the Director of National Intelligence did not respond to requests for comment.
Coats has in the past warned about the threat of Russian interference in U.S. elections -- in sharp contrast to language used by Trump. He has served as director of national intelligence, overseeing the nation's intelligence agencies, for two years; Trump appointed him.
He testified before the the Senate Intelligence Committee that foreign adversaries were "probably already are looking to the 2020 U.S. elections as an opportunity to advance their interests."
This year, he wrote that competitors such as Russia, China and Iran "probably already are looking to the 2020 U.S. elections as an opportunity to advance their interests."
Trump has often been critical of the the intelligence community since he took office, frequently referencing a "deep state" that he says opposes him.