The Södermalm district covers the island of the same name (formerly called Åsön), which, however, is not fully separated from the peninsula of Södertörn (or the rest of the Swedish mainland), as water to both its north and south does not flow freely but passes through a lock and a man-made waterway.

[1] Its first urban areas were planned and built in the mid 17th century, comprising a mixture of working class housing, such as the little red cottages of which a few can still be seen in northeastern Södermalm, and the summer houses and pavilions of wealthier families, such as Emanuel Swedenborg's pavilion, which is now in the outdoor museum Skansen.

Södermalm is often poetically named Söders höjder ("heights of the south"), which reflects its topography of sheer cliffs and rocky hills.

In the 18th century, the working-class cottages that clung to Mariaberget, the steep cliffs facing Riddarfjärden, were replaced by the large buildings that are still present today.

Meanwhile, the growing demand for housing, as well as an increasing gentrification of Stockholm's central parts, makes apartments in Södermalm more and more difficult or expensive to come by.