Moon and his spouse, first lady Kim Jung-sook, were greeted by Kim Jong-un and the North's first lady, Ri Sol-ju, at Pyongyang Sunan International Airport on Tuesday morning.
The two first ladies, who had displayed an exceptional rapport during their first meeting at the Moon-Kim summit in April in Panmunjom, are expected to cultivate their relationship further during this trip, which runs Tuesday through Thursday.
Kim Jung-sook's official itinerary for Tuesday included visits to the Kim Won-gyun Conservatory, a prestigious music school in Pyongyang, and the nearby Okryu Children's Hospital, accompanied by Ri.
The first ladies' trip to the music college will likely serve as a chance for the two to discuss their mutual love of music, given their music backgrounds.
Kim Jung-sook majored in vocal performance at Kyung Hee University in Seoul and was part of the Seoul Metropolitan Chorus, while Ri was a soloist with the North's famous Unhasu Orchestra before she married Kim Jong-un.
On Wednesday, the South Korean first lady's itinerary includes a visit to the Mangyongdae School Children's Palace, a massive facility on the southwestern edge of Pyongyang where North Korean children take classes in ballet, musical instruments, singing and calligraphy. Its students often perform for foreign reporters and tourists.
Former President Kim Dae-jung and his wife, Lee Hee-ho, visited the school in 2000.
North Korea observers have noted since earlier this year that the country's media now refer to Ri as "revered first lady," instead of "comrade" as they customarily used to. Ri also accompanied her husband to Beijing in March when Kim Jong-un made a surprise diplomatic debut at his summit with Chinese leader Xi Jinping.
This is the first inter-Korean summit held in Pyongyang in 11 years.