The person, who was not immediately identified by authorities, was taken to hospital.
“It’s definitely serious, but just how serious I can’t say,” police spokesman Mats Eriksson said.
The daredevil’s parachute did not open properly, resulting in a free fall from around the 15th floor of the building.
According to police, a second person also jumped from the same building at Kungsholmen on Saturday but that individual’s parachute opened properly.
It was not immediately clear if they had jumped from the top of the building or from an open window from one of its upper floors.