Kuusisto was first mentioned in 1295. The construction of the bishop's castle began in 1316. The island was a part of the Piikkiö parish. After the Reformation, the bishop's castle was demolished. Some of its remains were used as materials for the Piikkiö church in 1755. Kuusisto gained chapel rights in 1653, eventually becoming a separate municipality and parish in 1914. It was consolidated with Kaarina in 1946.[5][6]
As the municipality was disestablished before rural municipalities were allowed to use coats of arms, Kuusisto never had an official coat of arms. The heraldist Tapani Talari has designed an unofficial coat of arms for use by the Suomen Kuntaliitto ry.
Gallery
Bridge to Rövarholmen island in the southwest of Kuusisto Island
Yle broadcasting tower run by Digita Oy in the southwest of Kuusisto Island.