The Battle of Rennell Island (Japanese: レンネル島沖海戦, Hepburn: Renneru-shima oki kaisen) took place on 29–30 January 1943. It was the last major naval engagement between the United States Navy and the Imperial Japanese Navy during the Guadalcanal Campaign of World War II. It occurred in the South Pacific between Rennell Island and Guadalcanal in the southern Solomon Islands.

In the battle, Japanese land-based torpedo bombers, seeking to provide protection for the impending evacuation of Japanese forces from Guadalcanal, made several attacks over two days on U.S. warships operating as a task force south of Rennell Island. In addition to approaching Guadalcanal with the objective of engaging any Japanese ships that might come into range, the U.S. task force was protecting an Allied transport ship convoy carrying replacement troops there.

As a result of the Japanese air attacks on the task force, one U.S. heavy cruiser was sunk, a destroyer was heavily damaged, and the rest of the U.S. task force was forced to retreat from the southern Solomons area. Partly because they turned back the U.S. task force in this battle, the Japanese successfully evacuated their remaining troops from Guadalcanal by 7 February 1943, leaving it in the hands of the Allies and ending the battle for the island.