Kilwa Kisiwani (Kilwa Island) is an island, national historic site, and hamlet community located in the township of Kilwa Masoko, the district seat of Kilwa District in the Tanzanian region of Lindi in southern Tanzania. Kilwa Kisiwani is the largest of the nine hamlets in the town of Kilwa Masoko and is also the least populated hamlet in the township with fewer than 1,000 residents.

At its peak in the Middle Ages, Kilwa had over 10,000 inhabitants. Since 1981, the entire island of Kilwa Kisiwani has been designated by UNESCO as a World Heritage Site along with the nearby ruins of Songo Mnara. Despite its significant historic reputation, Kilwa Kisiwani is still home to a small and resilient community of natives who have inhabited the island for centuries. Kilwa Kisiwani is one of the seven World Heritage Sites in Tanzania. Additionally, the site is a registered National Historic Site of Tanzania.