The images of Kim posing and laughing with South Korean pop stars and applauding in the stands contrasts with reports from North Korean defectors who say he has overseen a crackdown on anyone caught listening to foreign media.
Another famed singer, Choi Jin-hee, is set to perform for the fourth time in the North and to sing "Maze of Love" - a pan-peninsula hit and one of the late Kim's favourites.
The North Korean leader even met with the girl group to take a photo after the show.
The theme of the joint concert will be "Spring is Coming", Hwang Seong-un, a spokesman for South Korea's culture ministry said at a briefing in Seoul on March 27. Seoul and Pyongyang are set to hold a summit on April 27, followed by the North's talks with U.S. on denuclearization before the end of May. "The issue of denuclearization of the Korean Peninsula can be resolved, if South Korea and the United States respond to our efforts with goodwill, create an atmosphere of peace and stability while taking progressive and synchronous measures for the realization of peace", Kim was quoted as saying by China's official news agency last week. He was also seen talking to members of Red Velvet, who have more than 4.6 million followers on Instagram. "Originally, I planned to come the day after tomorrow but I adjusted my schedule and came today".
"I thank you for this kind of gift to Pyongyang's citizens".
Kim asked the performers to tell South Korean President Moon Jae-in that the two Koreas should hold a similar event in Seoul in the autumn, according to South Korean media pool reports. While President Trump has referred to Kim as "little Rocket Man", my colleagues Emily Rauhala and Anna Fifield write that the regime's diplomatic outreach - including last week's visit to Beijing - are making it harder to dismiss the North Korean leader as irrational or as a madman.
The show's host Seohyeon of Girls' Generation, who performed with the North Korean art troupe in February in Seoul, welcomed the North Koreans to the show. There will be another event on Tuesday that will showcase the talents of South Korean acts.
The Korean Central Television (KCTV) on Monday aired footage showing Kim visiting the East Pyongyang Grand Theater on Sunday evening to watch the concert and encourage the performers.
Is this a start of a harmonious relationship between two countries? Smuggled across the border on USB sticks and bootleg DVDs, K-pop has spread widely among the families of North Korea's political elite, Kang said.
Kim had been planning to attend the Tuesday performance but made a decision to watch Sunday's show due to "political schedules", KCNA and South Korean officials there said.
It was unclear whether Kim Jong Un would make an appearance at the concerts.
A high-ranking North Korean official apologized to South Korean reporters for restricting access to a Pyongyang concert staged by major K-Pop artists.
As well, the of South Korean taekwondo demonstrators performed at the Pyongyang Taekwondo Hall I front of more than 2,300 north Koreans including Choe Hwi, chairman of the National Sports Guidance Committee.