According to the North Korean constitution, Kim Jong Un is part of a triumvirate heading the executive branch of the North Korean government along with Premier Kim Tok Hun and Supreme People's Assembly president Choe Ryong Hae. He is a grandson of Kim Il Sung, who was the founder and first supreme leader of North Korea from its establishment in 1948 until his death in 1994. The Supreme People's Assembly subsequently elected him first chairman of the National Defence Commission.

In 2018 and 2019, Kim took part in summits with South Korean president Moon Jae-in and US president Donald Trump, leading to a brief thaw between North Korea and the two countries, though the negotiations ultimately broke down without progress on denuclearization.Kim is expected to seek economic aid and military technology for his impoverished country, and appears to have something Putin desperately needs: munitions for Russia's grueling war in Ukraine. A statement issued by the country's official news agency the Korean Central News Agency used the rare expression "profound consolation and apology".

There have also been reports that citizens in North Korea were encouraged to sing a newly composed "song of praise" to Kim Jong Un, in a similar fashion to that of praise songs relating to Kim Jon Il and Kim Il Sung. On 30 November 2012, Kim met with Li Jianguo, member of the Politburo of the ruling Communist Party of China (CPC) and first-ranking vice chairman of the National People's Congress Standing Committee, who "briefed Kim on the 18th National Congress of the Communist Party of China", according to the state's official news agency, the Korean Central News Agency. The birth year of Kim Il Sung, 1912 in the Gregorian calendar, became " Juche 1" in the Juche calendar. In material pertaining to relations with foreign countries, "the Juche Era and the Christian Era may be used on the principles of independence, equality and reciprocity. On 11 April 2012, the 5th Session of the 12th Supreme People's Assembly appointed Kim Jong Un First Chairman of the National Defence Commission.On 30 June 2019, in the Korean DMZ, Kim again met with Trump, shaking hands warmly and expressing hope for peace. Kim has changed North Korea's internal power dynamics, increasing the influence of the WPK while decreasing the power of the military. The Korean Central News Agency (KCNA) described Kim Jong Un as "a great person born of heaven", a propaganda term only his father and grandfather had enjoyed. He has had his ups and downs under Kim Jong-un, but having weathered a few storms currently sits on the presidium of the politburo and is also first vice chairman of the State Affairs Commission. Yonhap has stated that, according to multiple unnamed sources, Kim Jong Un has also put to death members of Jang's family, to completely destroy all traces of Jang's existence through "extensive executions" of his family, including the children and grandchildren of all close relatives.

In the days that followed the country's announcement, hundreds of thousands of new cases of fevers were reported, as well as 27 related deaths related to fever of unidentified origins, among which one death was confirmed as from the Omicron variant according to state-media KCNA.Subsequent reports indicated that his name did not appear on the list of lawmakers, [42] but he was later elevated to a mid-level position in the National Defense Commission, which is a branch of the North Korean military. At the April 2018 inter-Korean summit, Kim and South Korean President Moon Jae-in signed the Panmunjom Declaration, pledging to convert the Korean Armistice Agreement into a full peace treaty, formally ending the Korean War, by the end of the year. References to Juche and Songun were replaced by Kimilsungism–Kimjongilism, and the constitution stipulated that the mission of North Korea's armed forces was to "defend unto death the Party Central Committee headed by the great Comrade Kim Jong Un"; this made Kim the first North Korean leader to be named in the constitution while currently holding power.