SEOUL, South Korea — North Korea’s leader, Kim Jong-un, put himself in charge of a new governing agency created during a meeting of his country’s rubber-stamp parliament, the Supreme People’s Assembly, on Wednesday.

The Assembly revised North Korea’s Constitution to create what the state media called a Commission on State Affairs, with Mr. Kim as its chairman. It replaces the National Defense Commission, the most powerful governing organ under Mr. Kim’s father, Kim Jong-il, who ruled North Korea until his death in 2011.

Mr. Kim’s new title was the latest in a series of top leadership roles in the military, party and government that he has acquired to establish his one-man rule.

Image North Korean leader Kim Jong-un was appointed as chairman of the newly created Commission on State Affairs on Tuesday. Credit... Wong Maye-E/Associated Press

Before his death, Kim Jong-il ruled North Korea as chairman of the National Defense Commission. Although the commission was originally created to oversee military affairs, he used it as his primary governing agency under his “military first” policy, which focused on the development of nuclear weapons and promoted the priorities of the Korean People’s Army in economic and other policy decisions.