Trump was said to have acted on "clear recommendations" from Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein.
Comey has been a controversial figure amongst both Democrats and Republicans - with the former for his curiously-timed letters about Hillary Clinton's private email server, and the latter for recent investigations into alleged ties with Russia.
Since the news broke, a number of high profile figures in the entertainment world have reacted to Comey's firing on social media.
TV hosts have also responded. The Daily Show's Trevor Noah taped a new episode moments after the news broke and said: "You can't just fire the FBI director. If he's gone, who's going to investigate Russia's ties to... oh."
Meanwhile Jimmy Kimmel opened his Late Night show on ABC by saying: "He fired the director of the FBI, while the director was investigating [Trump's] people and possible collusion with Russia.
Jimmy Kimmel on James Comey firing: 'This is the kind of thing dictators do'
"That's kind of like OJ firing Judge Ito halfway through the trial. This is unbelievable. This is the kind of thing dictators do."
Democrat Senator Nick Durbin has called on the White House to clarify whether the investigation will continue, and added that "any attempt to stop or undermine the FBI probe would raise grave constitutional issues".
Representative John Conyers, senior Democrat on the House Judiciary Committee, said: "[Today's] actions by President Trump completely obliterates any semblance of an independent investigation into Russian efforts to influence our election, and places our nation on the verge of a constitutional crisis."
The White House has indicated that a search for a new FBI director will begin "immediately".
Comey himself reportedly thought his removal was a prank, and learned that he had been sacked from TV news coverage while he was addressing employees in LA.
It is the second time in US history that a President has fired an FBI director.
/The Independent/
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