Starting in the 1750s, Shimoni, along with Malindi, Mombasa and other coastal cities and towns, was a primary, 'slave holding port,' for east Africa's coastal slave trade which reached from South Africa to the Middle East. These slave holding pens were located in the natural cave systems that exist in Shimoni. Currently, visitors are granted access to the Shimoni Slave Caves during the guided tour by members of the Shimoni Slave Cave Committee. In 1857, the British parliament enacted an international ban on the slave trade. In the 1870s, British parliament was successful in convincing Barghash ibn Sa'id, the Sultan of Zanzibar, to acknowledge the ban. This edict choked the trafficking of slaves to and from Zanzibar, effectively cutting off Shimoni's relevance in the slave trade.
In the 1880s, British colonialism began in Shimoni with the arrival of the British Imperial East Africa Company's headquarters. The British Imperial East Africa Company choose Shimoni because it was virtually uninhabited at the time. Many other buildings in Shimoni were built by the very first British colonists of Kenya, including Kenya's first colonial prison (now in ruins).
The first senior staff residence headquarters to be built by the Imperial British East Africa Company in the south coast in 1885
Over time it has developed from a sleepy fishing village to become the main port of clearance for ocean going trade Dhows arriving from as far away as the Arab states of the Persian Gulf, the island of Zanzibar and Dar es Salaam