The North’s Central TV showed Mr. Kim visiting an amusement park in Pyongyang together with a young stylish woman, and identified her as “Comrade Ri Sol-ju, wife of Marshal Kim Jong-un,” South Korean officials said. A North Korean state-run radio station also identified the woman as Mr. Kim’s wife.

In recent weeks, North Korean media has shown the same woman accompanying Mr. Kim in several state functions, triggering speculation over who she was. The couple attended a July 6 concert that featured Mickey Mouse and other Disney characters. They later visited a kindergarten together.