In a video posted shortly thereafter, he defended his conduct and suggested he may be immune from the virus.
"Don't let it dominate you. Don't be afraid of it," he said.
"You're gonna beat it. We have the best medical equipment, we have the best medicines, all developed recently. And you're gonna beat it. I went, I didn't feel so good, and two days ago, I could have left two days ago, two days ago I felt great, like better than I have in a long time. I said just recently, better than 20 years ago."
"I know there's a risk. There's a danger. But that's OK. And now I'm better. And maybe I'm immune, I don't know," he continued.
"But don't let it dominate your lives. Get out there, be careful, we have the best medicines in the world. And it all happened very shortly, and they're all getting approved, and the vaccines are coming momentarily."
So far, the coronavirus has killed more than 200,000 people in the US.
Earlier, Mr Trump left the hospital wearing a mask, clenched his fist for the cameras and walked away without assistance. He then boarded an aircraft back to the White House.
Mr Trump’s doctor Sean Conley told reporters he was well enough to leave the hospital.
"He may not be entirely out of the woods yet," Dr Conley said.
"But the team and I agree that all of our evaluations, and most importantly his clinical status, support the president's safe return home, where he'll be surrounded by world class medical care."
It comes after White House Press secretary Kayleigh McEnany announced she had tested positive for COVID-19.
She said in a statement that she had tested negative ever since Mr Trump's own diagnosis last week but "I tested positive for COVID-19 on Monday morning while experiencing no symptoms."
Ms McEnany - the combative, main public interface between Mr Trump and the media, giving daily television interviews and holding frequent briefings - said that no journalists were believed to have come into close contact with her.
The news rammed home just how infected the White House has become.
Cases now include Mr Trump's wife Melania, his close aide Hope Hicks, his campaign manager Bill Stepien, and more than half a dozen others from the president's circle both inside and outside the White House.
Donald Trump 'not out of the woods yet' but cleared to leave hospital
Early Monday, a stream of election slogans, all in capital letters, filled Mr Trump's Twitter feed.
Late Sunday, he drew criticism from independent medical experts by making a brief sortie in an armoured SUV to drive past a crowd of supporters gathered nearby.
The White House published photos over the weekend of Mr Trump working in his hospital suite and he tweeted two videos in which he talks about his recovery.
Source: Joyce N.Boghosian/Sipa USA
The rosy image built up by Mr Trump is running up against snippets of more alarming information given by doctors over the past few days, including that he had been given the steroid dexamethasone and two experimental drugs - a cocktail more usually associated with serious COVID-19 cases.
Dr Conley also said in a Sunday briefing that Mr Trump had indeed been given extra oxygen after a "rapid progression" of his illness and falling oxygen levels on Friday.
He said he had initially held back this crucial information to reflect the "upbeat attitude."
Additional reporting by Reuters.
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