Pompeo was dispatched on an unannounced visit — his second in weeks, but first as secretary of state — to lay the groundwork for Donald Trump’s unprecedented meeting with Kim Jong Un.
His visit also comes as rumours fly over the fate of three US citizens being held in the North, with suggestions they may have been moved in preparation for a release.
Previous detainees have been set free into the care of high profile US visitors.
Pompeo’s itinerary — including who he would meet in Pyongyang — was not clear.
Trump, who had repeatedly threatened to attack North Korea, now appears focussed on diplomacy.
“We think relationships are building with North Korea. We will see how it all works out. Maybe it won’t. But it can be a great thing for North Korea, South Korea and the entire world,” Trump said in a televised address from the White House.
After years of tensions and ever-tightening sanctions over North Korea’s nuclear and missile programmes, a detente on the peninsula has rapidly gathered pace.
On Tuesday, Kim met Chinese President Xi Jinping in China — the second time in six weeks — highlighting efforts by the Cold War-era allies to mend frayed ties.
Beijing is keen to avoid being left out in the cold in the diplomatic manoeuvres that led to Kim’s historic summit last month with South Korean President Moon Jae-in and his expected meeting with Trump.
Pompeo’s visit also comes as a tripartite meeting of East Asia’s major powers takes place in Tokyo, with Japan, South Korea and China groping for a lowest-common-denominator agreement on recent events.
Japan, which has by far the most hardline position of the North’s neighbours, has been left watching from the sidelines, uneasy at the pace of events and at what it sees as an unwarranted softening towards an untrustworthy Pyongyang.
Japanese Prime Minister Shinzo Abe is likely to push for continued pressure on Pyongyang, including for “complete, verifiable and irreversible denuclearisation”, Japanese media have reported.
Moon, however, is expected to bat away such demands.
An official in his office last week said Seoul wanted the three countries to simply endorse the Panmunjon Declaration signed by Kim and Moon last month in the Demilitarized Zone that separates the two Koreas.