White House statements said he was dismissed over the Clinton email investigation, which was widely credited with swinging the election in Mr Trump’s favour and saw him label his rival “crooked Hillary” and lead chants of “lock her up” at rallies.
After recommending no charges be brought over her handling of classified information, the FBI director was leading a probe into alleged links between the Trump administration and Russia.
There were concerns that Mr Trump's discussions with Russian officials may further damage his relationship with American and foreign intelligence agencies, ahead of his first overseas trip.
White House officials reportedly took steps to contain the damage, placing calls to the CIA and the National Security Agency. Republicans and Democrats have expressed concern about the reports amid mounting fears for the Trump administration's international credibility.
"As President I wanted to share with Russia (at an openly scheduled W. meeting) which I have the absolute right to do, facts pertaining..terrorism and airline flight safety," he wrote.