[1] The district is comparable in size to the land area of the nation state of East Timor.

The sultanate of Kilwa is reputed to have been founded about 975 by Ali ibn Ḥasan, a Persian prince from Shiraz.

The new state, at first confined to the town of Kilwa, extended its influence along the coast from Zanzibar to Sofala, and the city came to be regarded as the capital of the Zanj region.

An Arab chronicle gives a list of over forty sovereigns who reigned at Kilwa in a period of five hundred years,[5][6] and the region was transformed into one of the wealthiest Swahili city states on the continent by the 14th century.

Kilwa district is known globally for its Middle Ages Swahili historical sites from Middle Ages on the islands Kilwa Kisiwani and Songo Mnara which are part of the seven Tanzanian World Heritage Site.

Towards the end of the 17th century it fell under the dominion of the imams of Muscat, and on the separation in 1856 of their Arabian and African possessions became subject to the sultan of Zanzibar.

In 1918 when Tanganyika became a British protectorate, Kilwa Masoko was chosen as it is the district seat and they built a deepwater port to assist with their commercial vessels.

Kilwa District is home to Pindiro Forest Reserve where albino hippopotamuses have been observed.

The soil structure of Kilwa district is of low fertility is mostly made of well-drained, low-moisture retaining sedimentary sandstone.

As mentioned in the history section of this article Kilwa district is the ancestral home of the Mwera, Matumbi and Machinga Shira.

The main crops grown for local consumptions includes, cassava, maize, sorghum and African rice.

Due to Tsetse fly, livestock rearing is restricted on the west part of Kilwa district.

4.5 million tons of fish are harvested annually with over 1700 registered fishermen using 600 vessels in the district.