Korean Workers' Party newspaper Rodong Sinmun reported Thursday that Kim attended the event the day before with first lady Ri Sol Ju. The ruling family was last seen attending a concert together in April on the 109th birth anniversary of Kim Il Sung.
State media said the military audience greeted Kim and Ri with loud cheers hailing the North Korean leader. Shouts "rang through the hall," according to the Rodong.
Kim reportedly expressed gratitude and "great satisfaction" about the performance, which was described as ideologically correct and "culturally significant."
"Military families have become the faithful interpreters of Party policy," Kim said.
The performance Kim attended was the "great fruit of the focus on the righteousness and life force provided by the mass culture and the arts." The ruling party "constantly" has placed weight on the role of culture for policy, the North Korean leader said.
"It is something to be proud of that the Korean People's Army is always exemplary in the implementation of the Party's mass culture and arts policy," Kim said.
"The whole country must learn to follow the passionate patriotism, tenacious life force, and high ideological spirit of the military families."
North Korea's KCNA published photos showing theater attendees all wearing masks with the exception of Kim, Ri and top officials Jo Yong Won, Ri Byong Chol and Pak Jong Chon.
At the Eighth Party Congress in January, all Party members were seen without masks when in the presence of Kim Jong Un.
Analysts in the South said it is likely North Korea is stepping up anti-epidemic measures in connection to COVID-19, Yonhap reported Thursday.
State media also recently disparaged the effectiveness of COVID-19 vaccines and stressed the importance of quarantine regulations, the report said.