KCNA news agency reports that the North Korean leader cut the ribbon at the opening of a fertiliser factory.
It adds that people at the factory "broke into thunderous cheers of hurrah" when he appeared.
The reported appearance - his first since an event on state media on 12 April - comes amid global speculation over his health.
The latest reports from North Korean media could not be independently confirmed.
State media later released images that it said showed Mr Kim cutting a ribbon outside a factory.