The president received an experimental drug before heading to a military hospital in Washington, where his condition will be monitored over the weekend.
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”.
Mr Trump was given treatment at the White House including “very potent” experimental artificial antibody REGN-COV2, which is made by Regeneron Pharmaceuticals.
He then travelled in a helicopter to Walter Reed National Military Medical Centre on Friday afternoon as a precaution, according to medics.
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 said “I think I’m doing very well but we’re going to make sure things work out”.
Mr Trump’s doctor, navy commander Dr Sean Conley, said on Saturday morning local time that the president has not had a high temperature for 24 hours.
Doctors say the president told them: “I feel like I could walk out of here today.”
A person familiar with Mr Trump’s Covid-19 illness disputed this, saying some of his vital signs over the past 24 hours were “very concerning”, but they have improved since he was admitted to hospital, according to the Associated Press.
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.
Mr Trump tweeted on Saturday: “Doctors, Nurses and ALL at the GREAT Walter Reed Medical Center, and others from likewise incredible institutions who have joined them, are AMAZING!!!
“Tremendous progress has been made over the last 6 months in fighting this PLAGUE. With their help, I am feeling well!”