The President has been angry with Sessions since his recusal from an investigation into Russia’s role in the 2016 presidential race.
He has now inserted in his place a Republican Party loyalist - Matthew Whitaker - with authority to oversee the remainder of special counsel Robert Mueller’s investigation.
Whitaker, until now Sessions’s chief of staff, has questioned the inquiry’s scope and spoke publicly before joining the Justice Department about ways an attorney general could theoretically stymie the probe.
Sessions’ departure was widely expected to come soon after Tuesday’s congressional elections in which the Republicans retained their majority in the Senate but lost control of the House of Representatives.
Trump announced Sessions’ departure on Twitter. Sessions said in a letter to Trump he resigned at the president’s request.
Mueller, operating under the auspices of the Justice Department, is pursuing a wide-ranging Russia investigation that already has yielded a series of criminal charges against several of Trump’s associates and has dogged his presidency.
Trump was only a few weeks into his presidency in March 2017 when Sessions upset him.
Rejecting White House overtures, Sessions stepped aside from overseeing the FBI’s probe.
Sessions cited news reports of previously undisclosed meetings he had with Russia’s ambassador to Washington as his reason for recusal.
Deputy Attorney General Rod Rosenstein took over supervision of the Russia investigation and in May 2017 appointed Mueller as the Justice Department’s special counsel to take over the FBI’s Russia probe after Trump fired FBI Director James Comey.
Rosenstein also has faced criticism from Trump.
Whitaker said in a statement that he was committed to “leading a fair department with the highest ethical standards, that upholds the rule of law, and seeks justice for all Americans”.
Congressional Democrats, concerned about protecting Mueller, called on Whitaker to recuse himself from overseeing the investigation in its final but potentially explosive stages.
Representative Jerry Nadler, the top Democrat on the House Judiciary Committee, said he wants “answers immediately” and “we will hold people accountable”.