Kilwa Masoko or Masoko is an administrative ward in Kilwa District of Lindi Region in Tanzania. The ward covers an area of 200 km2 (77 sq mi), and has an average elevation of 11 m (36 ft). The ward is also the capital of Kilwa District. According to the 2012 census, the ward has a total population of 13,601.

Kilwa District is one of six administrative districts of Lindi Region in Tanzania. The District covers an area of 15,000 km2 (5,800 sq mi). The district is comparable in size to the land area of the nation state of East Timor. Kilwa district is bordered to the north by Rufiji District in Pwani Region, to the east by the Indian Ocean, to the south by the Lindi District, Nachingwea District together with Ruangwa District, and to the west by the Liwale District. The district borders every other district in Lindi Region except Lindi Municipal District. The district seat (capital) is the town of Kilwa Masoko. The district is named after the medieval Swahili city state of Kilwa Kisiwani. According to the 2012 census, the district has a total population of 190,744. By 2022, the population had increased to 297,676.