The president tweeted to say he would meet them when they land in the early hours.
He said: “I am pleased to inform you that Secretary of State Mike Pompeo is in the air and on his way back from North Korea with the 3 wonderful gentlemen that everyone is looking so forward to meeting. They seem to be in good health. Also, good meeting with Kim Jong Un. Date & Place set.”
Mr Trump added: “Secretary Pompeo and his ‘guests’ will be landing at Andrews Air Force Base at 2:00 A.M. in the morning. I will be there to greet them. Very exciting!”
The prisoners – Kim Dong Chul, Kim Hak Song and Tony Kim – were accused by North Korea of anti-state activities.
Mr Pompeo had said “it would be a great gesture” if the men were freed.
Mr Trump’s national security adviser, John Bolton, added that releasing them would be “an opportunity” for the North to “demonstrate their authenticity.”
Kim Dong Chul, a South Korea-born pastor, was arrested in 2015 and accused of spying.
A year later, he was sentenced to 10 years’ hard labour.
The two other men were working at Pyongyang University of Science and Technology, founded by evangelical Christians from overseas, when they were arrested last year and accused of “hostile acts”.
Until now, the only American to have been freed from North Korea during the Trump presidency is Otto Warmbier, who returned to the US in a coma and died. He had been captive for 17 months.
Mike Pompeo was in the country to finalise details of the meeting between Mr Trump and North Korean leader Kim Jong Un.
Details of the location and timing of the summit have not yet been made public.
On Wednesday, Mr Pompeo met Kim Yong Chol, vice chairman of the central committee of North Korea’s ruling party, for lunch.
The pair discussed the possible agenda for the meeting between their leaders.
It was Mr Pompeo’s second trip to North Korea – he visited at Easter before he was officially appointed as America’s top diplomat.
The release of the prisoners is the latest move in a remarkable thaw in relations between the North Korea and the West that has seen Kim Jong Un promise to give up his nuclear programme.
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The leaders of North and South Korea recently held their first meeting in more than a decade, with the men joining hands as they stepped across their joint border.