Thanking Tillerson for his service on Twitter, President Trump said the new state secretary would do “a fantastic job”.
Tillerson, a former chief executive of ExxonMobil, was only appointed to the job just over a year ago.
The president also nominated Gina Haspel to become the first woman director of the CIA.
The Department of State said Tillerson had not spoken to the president and was “unaware of the reason” for his firing.
Under Secretary Steve Goldstein said: “The Secretary had every intention of staying because of the critical progress made in national security.”