Kim's appearance contradicts recent rumours that he was gravely ill
Kim Jong-un has warned North Korean authorities to prepare for the dangers posed to the country by the coronavirus pandemic and a looming typhoon.
Mr Kim's appearance at a party meeting comes after widespread speculation over his health.
North Korea has not confirmed any Covid-19 cases and it is thought that a large outbreak would have a devastating effect on the impoverished nation.
Meanwhile Typhoon Bavi is expected to hit North Korea later this week.
Speaking at a meeting of the politburo on Tuesday, Mr Kim, who was smoking a cigarette, said there were “some shortcomings” in the state's efforts to keep out the “malignant virus”, state media reported, without giving details.
Pyongyang for a long time insisted there were no infections in the country, though this was doubted by observers. No cases have been declared, but its media have not repeated the claim for several weeks now.
After a suspected case, there had been a lockdown in one border city near South Korea but the infection was never officially confirmed.
Kim Jong-un's appearance came amid rumours about his health and that he had delegated some of his authority to his sister Kim Yo-jong.
Speculation about the health of the North Korean leader is not unusual but has so far always turned out to be false.
Analysis box by Laura Bicker, Seoul correspondent
While the world's tabloids obsess over Kim Jong-un – who is clearly fine – there are bigger concerns. The state and its 25 million people are clearly not fine.
Typhoon Bavi could cause damage in a country already reeling from one of the longest monsoon seasons on record. Torrential rain in August brought widespread flooding.
And now the BBC's weather centre is predicting storm surges of between 200-300mm of rain just weeks before the autumn rice harvest.
Ten million people are said to suffer from food insecurity in North Korea, according the UN. That means they live from harvest to harvest. They cannot afford more crops to be damaged.
North Korea has also gone from insisting it had zero cases of Covid-19 to holding yet another high level meeting to discuss ways to mitigate the effects of the virus.
We still don't know if outbreaks are under control in the secretive state, which closed its borders to the world in January.
Just last week, Mr Kim admitted that his big economic plan, which was due to come to fruition in 2020, had failed and he was having to come up with a new one. A rare admission from a North Korean leader that he has come up short.
Trade with China, the nation's biggest benefactor and ally, was down over 20% in July, according to Chinese customs data. Border closures to prevent coronavirus entering the country have had an impact on the vital supply chain.
NK News has also reported that foreign embassy staff and the majority of NGO's in the country have left due to the severe virus restrictions.
2020 has been a bad year for most of the world. But for North Korea it has the potential to be devastating and there are very few organisations available in the country to notice and help.