Beagle Channel is a strait separating islands of the Tierra del Fuego archipelago, in extreme southern South America. It separates Isla Grande de Tierra del Fuego from several smaller islands to the south. Its eastern portion is part of the border between Chile and Argentina, but the western part is completely within Chile. Beagle Channel is about 150 miles long and is about three miles wide at its narrowest point. Although it is navigable by large ships, there are safer waters to the south (Drake Passage) and to the north (Strait of Magellan). Several small islands near the eastern end were the subject of a long-running territorial dispute between Chile and Argentina; by the terms of a 1985 treaty they are now part of Chile. (See Picton, Lennox and Nueva.)

The main settlements on the channel are Puerto Williams, Chile and Ushuaia, Argentina.

It is named for the HMS Beagle, the ship with which Charles Darwin explored the area in the 19th century.