The move comes with just a month to go until the US election.
Here are some of the events which have led up to his hospitalisation.
White House aide Hope Hicks is among a group of people who travel with Mr Trump to a fundraiser in Minnesota and an outdoor rally in Duluth.
She feels unwell on the return trip and isolates herself aboard Air Force One.
Ms Hicks tests positive for coronavirus.
Mr Trump travels to a private fundraiser in New Jersey.
He later announces that he and the First Lady Melania Trump are being tested for Covid-19 and they will go into quarantine.
In the early hours of the morning, Mr Trump tweets that he and his wife have tested positive for Covid-19.
In a statement, Dr Sean Conley, the president’s physician, says the couple “are both well at this time, and they plan to remain at home within the White House during their convalescence”.
Mr Trump is said to have “mild symptoms”.
— Kayleigh McEnany 45 Archived (@PressSec45) October 2, 2020
Press secretary Kayleigh McEnany says Mr Trump is “fatigued but in good spirits” and is being evaluated by experts.
A White House official later states that Mr Trump is to travel by helicopter to Walter Reed National Military Medical Centre.
Images show Mr Trump walking from the helicopter while wearing a mask and at a distance from other people on the flight.
In a video on Twitter, the president says “I think I’m doing very well but we’re going to make sure things work out”.
The White House says he will continue to work while he is at the medical centre and he has not handed over his powers to Vice President Mike Pence.