The KCNA agency said on Tuesday that Mr Kim "gave field guidance" at a newly built scientists' residential district.
Rodong Sinmun daily newspaper carried several photographs of Mr Kim using a walking stick as he inspected the site.
The absence of the 32-year-old leader had prompted a flurry of speculation about his health.
Some observers said Mr Kim could be suffering from gout or problems in his hip joint. Others even questioned if he remained in control of the state.
Analysis: Stephen Evans, BBC News, Seoul
The photographs are still pictures so it's impossible to know how easily Kim Jong-un is walking - did he walk for long, was he standing simply for the photographer?