Mr Trump, who is still contagious, removed his mask on the balcony of the White House, while posing for pictures.
His physician said he would continue treatment from there, and he “may not entirely be out of the woods yet”.
Several of Mr Trump’s staff and aides have also tested positive for the virus in recent days.
Questions remain over the seriousness of Mr Trump’s illness after a weekend of conflicting statements.
The US remains the country worst-hit by Covid-19, with 210,000 deaths and 7.4 million cases.
Mr Trump’s diagnosis has upended his campaign for a second term in office, less than a month before the Republican president faces Democratic challenger Joe Biden in the presidential election.
What happened during Trump’s return?
Wearing a navy business suit, tie and mask, Mr Trump walked out of Walter Reed National Military Medical Center in the Washington DC suburbs on Monday evening pumping his fist.
After a short helicopter ride, Mr Trump was pictured alone on the Truman Balcony of the White House. He removed his protective face mask, before giving a thumbs-up and a military-style salute.
A couple of hours later, he tweeted a campaign-style clip of his return set to stirring music.
Mr Trump also recorded a video message, urging Americans to get back to work.
“You’re going to beat it [coronavirus],” he told them, adding: “We’re going to be out front. As your leader, I had to do that. I knew there’s danger to it, but I had to do it. I stood out front, and led.”
Mr Trump also speculated: “Now I’m better, maybe I’m immune, I don’t know”.
The World Health Organization says it is too early to know if people who have recovered from Covid-19 are protected from a second infection, and if so, how long this protection might last. The president’s own medical team does not consider him to be fully recovered yet.
Mr Trump also promised that vaccines were “coming momentarily”, although the US Centers for Disease Control has said no vaccine is expected to be widely available before the middle of next year.
Before leaving hospital, the president told Americans in a tweet not to fear the disease and said he would be back on the campaign trail “soon”.
Democratic presidential nominee Joe Biden said he was “glad” the president appeared to be “coming along pretty well”.
But he criticised Mr Trump, saying: “Anybody who contracts the virus by essentially saying masks don’t matter, social distancing doesn’t matter, I think is responsible for what happens to them.”
According to US public health guidelines, Mr Trump should remain in isolation for up to 10 days after symptoms first appear. The White House says the president first started to appear ill on Thursday evening, and later tested positive.
-BBC