Långholmen is a park and recreation area with bathing spots, including a beach bath and rocky bathing areas. The island also has playgrounds, a sports field, an outdoor theatre, allotment gardens, jetties and places to store boats. In winter, sledging is popular in the park.

The former prison is now a hotel and hostel, with a prison museum. Other historic buildings include Karlshälls gård and Stora Henriksvik, which has a small Bellman museum and café. Mälarvarvet, one of Stockholm’s oldest boatyards, is on the island’s eastern side. Visit Stockholm says that the island was a prison from the 18th century until 1974.

Six places on Långholmen have cultural remains registered by Sweden’s National Heritage Board, including a rock carving and boat remains in the water north of the island. Långholmsparken was laid out around the turn of the 20th century. After dredging in Pålsundet in the 1870s, earth was spread over the rock and about 2,400 trees were planted.