Trump announced in a tweet that Sessions' chief of staff Matt Whitaker would become the new acting attorney general.
Trump has gone after the Justice Department and Sessions over the ongoing investigation into ties between the Trump election campaign and Russian Federation by special counsel Robert Mueller.
In an interview on "CNN Newsroom", Dean said the ouster was "unlike the Saturday Night Massacre" of October 1973, when the embattled Nixon fired special prosecutor Archibald Cox, and accepted the resignations of his attorney general and deputy attorney general amid the Watergate scandal.
For more than a year, Trump has blamed Sessions for recusing himself from overseeing the Russian Federation election tamper investigation, which, in turn, led to the appointment of Special Counsel Robert Mueller.
Jeff Sessions has been forced out as attorney general.
"Special Counsel Mueller must be allowed to complete his work without interference". He was a vocal critic of Mr Mueller, arguing in an op-ed for CNN a year ago that the probe should not go into the finances of Mr Trump and his family members.
Another Kavanaugh accuser admits to fabricating rape story
Jane Doe will get no media attention, but I am deathly afraid of revealing any information about myself or my family. Supreme Court, is going to break tradition "due to security concerns", the Supreme Court has announced .
The relentless attacks on Sessions came even though the Alabama Republican was the first USA senator to endorse Trump and despite the fact that his crime-fighting agenda and priorities - particularly his hawkish immigration enforcement policies - largely mirrored the president's.
It's unclear how long Mr. Trump will take to select a new permanent attorney general. The recusal left the investigation in the hands of Rosenstein, who appointed Mueller as special counsel two months later after Trump fired then-FBI Director James Comey.
Sessions resigned at the request of the president. The president has repeatedly belittled Sessions in public and expressed regret about appointing him. The attorney general, for his part, proved determined to remain in the position until dismissed.
There is some question whether Mr Sessions was sacked or resigned.
Sessions left the Justice Department for the last time Wednesday evening, flanked by a crowd of well-wishers. Trump tweeted. When asked about changes to his administration in a press conference earlier Wednesday, Trump did not mention Sessions.
"You can't blame Sessions for recusing himself!"
Sessions also touted the Justice Department's efforts to address crime, immigration, and the opioid crisis, among other issues. Sessions was a close campaign aide, attending national security meetings and introducing him at rallies in a red "Make America Great Again" hat. The undated letter was then sent to the White House. Sessions rejected the entreaty.
The Citizens for Responsibility and Ethics in Washington (Crew) watchdog group called on Congress to protect Mr Mueller's job and investigation, saying in a statement: "So far they have refused, because congressional leaders did not believe there was an immediate threat".