Brownsea Island by third parties, is owned by the National Trust. Most of the buildings are situated near the small landing stage. The northern portion of the island is a Nature Reserve managed by Dorset Wildlife Trust and an important habitat for birds; this part of the island has limited public access. A small portion to the southeast of the island, along with Brownsea Castle, is leased to the John Lewis Partnership for use as a holiday hotel for staff, and is not open to the public. The island forms part of the Studland civil parish in the Purbeck local government district.
Brownsea Island north of the island, the Scout and Guide Movements were allowed to return and the castle was renovated and leased to the John Lewis Partnership for use as a staff hotel. The island was opened to the public in May 1963 by Olave, Lady Baden-Powell, the Chief Guide, at a ceremony attended by members of the 1907 camp. Soon after Brownsea Island was opened to the public, it was attracting more than 10,000 visitors a year. Larger boats means that today the island attracts some 110,000 visitors annually. Since 1964 the island has been host to the Brownsea Open Air