Kungsholmen is an island in Lake Mälaren in Sweden, part of Stockholm City. It is situated north of Riddarfjärden and considered part of the historical province Uppland. Its area is 3.9 km² with a perimeter of 8.9 km. The highest point is at Stadshagsplan (47 m). The total population is 56,754 (December 31, 2007).

Administratively, it is subdivided into the five districts Kungsholmen, Marieberg, Fredhäll, Kristineberg and Stadshagen.