Both also attended the inter-Korean summit with South Korean president Moon Jae-In late last month.
"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".
1News US correspondent Rebecca Wright told Kate Hawkesby the trio are in good spirits and good health. "Date & Place set", Trump wrote.
The three Korean-Americans released by North Korea had spent many months trapped in the country.
Speaking at a news conference on Wednesday, the US President also ruled out meeting Mr Kim at the demilitarised zone which separates North and South Korea.
Kim Dong-chul, Kim Sang-duk and Kim Hak-song were turned over to US Secretary of State Mike Pompeo, who flew to Pyongyang amid preparations for an upcoming summit between Trump and Kim.
In quitting the Iran nuclear deal, Trump pitted the USA against some of its closest allies and leaving the future of Tehran's nuclear ambitions in question.
Trump broke the news on Twitter earlier Wednesday that the detainees were on their way back to the US with Secretary of State Mike Pompeo.
The White House says President Donald Trump views North Korea's release of three American citizens "as a positive gesture of goodwill". "We're prepared to meet with anyone who is speaking on behalf of the North Korean government and can give us solid answers so we're prepared", he said.
Minutes later, Pompeo arrived in Japan to refuel before flying on to Pyongyang.
The North Korean official then advised that the releases would follow a "very brief ceremony" - which he described as more like a legal process.
The president said the meeting will last at least one day, possibly two.
"What happens? Who knows". Mr Trump also referred to the North Korean leader as "Little Rocket Man".
Kim was quoted by China's official news agency Xinhua as saying on Monday, "I hope to build mutual trust with the USA through dialogue". Previous U.S. efforts to negotiate an end to the North's nuclear weapons program failed under Presidents Clinton and George W. Bush.
"Now we are hopeful that we can work together to resolve this conflict, take away threats to the world and make your country have all the opportunities your people so richly deserve", Pompeo said before lunch at the Koryo Hotel, a large, double-towered building in central Pyongyang.
"We must lead the ongoing momentum toward complete denuclearization of the Korean Peninsula and achieve peace and stability in northeast Asia", Japanese Prime Minister Shinzo Abe said at a joint news conference in Tokyo after their trilateral summit.
Bolton himself said the USA was looking for a "real deal" with Pyongyang that would include "the elimination of both the front and the back end of the nuclear fuel cycle; no uranium enrichment; no plutonium reprocessing".