Osu Castle is a castle located in Osu, Ghana on the coast of the Gulf of Guinea in Africa.
A substantial fort was built by Denmark-Norway in the 1660s, thereafter the fort changed ownership between Denmark-Norway, Portugal, the Akwamu, Britain, and finally post-Independence Ghana. Under Denmark–Norway control it was used to hold and dispatch enslaved people overseas.
In 1902, Osu Castle became the seat of government in Ghana but this has now moved to Golden Jubilee House.