Brunswick Peninsula (Spanish: Península de Brunswick) is a large peninsula in Magallanes y la Antártica Region, Patagonia, Chile, at . It is 16 kilometres (9.9 mi) wide at its base in the north, and almost 80 kilometres (50 mi) in the south. It measures 115 kilometres (71 mi) in length from the base to Cape Froward, the southernmost point of the American mainland. This yields an area of more than 6,300 square kilometres (2,400 sq mi).
The only city in the Peninsula is Punta Arenas, the regional capital. While the settled part of Punta Arenas is located at the east coast, all of the peninsula is part of the commune (municipality) of Punta Arenas, plus some large, and many small, mostly uninhabited nearshore islands like Isla Capitán Aracena, Clarence Island (south) and Dawson Island (southeast). In the northwest, the peninsula borders the commune of Laguna Blanca, and in the northeast, San Gregorio.