San Giovanni Suergiu, Santu Giuanni de Suergiu in sardinian language, is a comune in the Province of South Sardinia in the Italian region Sardinia, located about 50 kilometres west of Cagliari and about 4 kilometres south of Carbonia. San Giovanni Suergiu borders the following municipalities: Carbonia, Giba, Portoscuso, Sant'Antioco, Tratalias.