Kim Jong-un, Kim's wife Ri Sol-ju, and his powerful sister, Kim Yo-jong, as well as ceremonial head of state, Kim Yong-nam, were also in attendance in Pyongyang on Sunday, according to Associated Press via South China Morning Post.
After the performance Kim and his wife met with the performers and shook hands with every singer.
Meanwhile, one of North Korea's top officials, Kim Yong-chol, has apologised to South Korean reporters who had hoped to cover the performance after all but one were barred from entering the Grand Theatre, South Korean Yonhap news agency reports.
The K-pop singers will be performing one more time before they leave the North Korean capital.
Even leader Kim acknowledged that there had been "so much interest in whether I'd come to see Red Velvet or not".
The entire delegation, 186 people including South Korean government officials, reporters, technicians and staff, was scheduled to depart from Pyongyang at midnight and arrive at Incheon International Airport at around 1:30 a.m. today. The significant thaw in the inter-Korean relations has led them to set a date for their first summit in more than a decade on April 27.
"The whole goal of cultural exchange is to open the gates for better relations between the North and the South, which have been strained for a decade", said Kang Dong-wan, a professor at Dong-a University and a leader of the Busan Hana Center, an institute that helps North Korean defectors in the South Korean port city of Busan. Seohyun, who got her start as a member of the internationally acclaimed group Girls' Generation, was also there as a solo performer.
"There are stories in my hometown of a man who was interrogated for watching a South Korean drama, and was killed during interrogation - officers are very brutal", said Lee Hyeon-seo, a prominent defector who has met US President Donald Trump and is the author of the worldwide bestseller "The Girl with Seven Names", her autobiography.
The 26-second South Korean video clip showed a quiet audience when members of Red Velvet, wearing clothes less revealing than their normal stage costumes, danced and sang their popular hit song "Red Flavor". A group of South Korean taekwondo performers who held two demonstrations in Pyongyang attended a different reception hosted by Choe Hwi, chairman of the North's National Sports Guidance Committee.
Kim Yo-jong also became the first member from Pyongyang's ruling family to visit South Korea since the end of the 1950-53 Korean War.
North Korea did not ask for any change in choreography or song lyrics, according to music director Yoon Sang and the South's protocol officer for the president's office.
Band member Seulgi said she cried when North and South Koreans sang together the song, "Our Wish is Unification".
Kim offered an apology on behalf of North Korean authorities, saying that the restriction was not intentional.
The ongoing cooperation steps between the rivals began after North Korea took part in February's Winter Olympics in Pyeongchang, South Korea.
Another wrote: 'If you think it's such an "honour" to have shaken his hand, then go stay with Kim Jong Un up there. While Trump and Moon have said they will keep applying "maximum pressure" to the North, the exercises were delayed until after the Winter Olympiad finished on March 18.