Soyo is a city and municipality located in the province of Zaire in Angola. It is situated at the mouth of the Congo River and has a municipal population of 221,555.
Historically, Soyo was a significant site of conflict involving the Kingdom of Kongo, Portuguese Angola, and the Dutch West India Company. During the 17th century, it became an independent state and exerted considerable influence on politics within the Kingdom of Kongo during the Kongo Civil War.