Cacheu is a town in north western Guinea-Bissau, lying on the Cacheu River. Population 9,849 (2008 est).

The town of Cacheu is situated in territory of the Papel people.

Cacheu was one of the earliest European colonial settlements in sub-saharan Africa, due to its strategic location on the Cacheu river. Cacheu developed a European/Afro-European population from the late fifteenth century through informal settlement of Cape Verdian and Portugues traders, adventurers and outcasts (lancados). The authorities in mainland Portugal also sent to Cacheu degregados - people condemned to exile for a variety of offences.

For most of the seventeenth and eighteenth centuries, Cacheu was the official slave trading point for the Portuguese in the Upper Guinea region - the point at which duties on all slaves exported had to be paid.

Notable buildings in Cacheu include the Portuguese-built 16th century fort, dating from the period when Cacheu was a centre for the slave trade.

Roads in the town are paved with oil palm kernels. Other attractions in the town include the Tarafes de Cacheu Natural Park mangrove swamp and a regular market.