Castel di Lucio is a comune located in the Province of Messina within the Italian region of Sicily. It is situated approximately 90 kilometres southeast of Palermo and about 110 kilometres southwest of Messina.
The municipality is positioned in the northwestern section of the Nebrodi mountain range. Geographically, it borders the municipalities of Geraci Siculo, Mistretta, Nicosia, Pettineo, and San Mauro Castelverde. In terms of ecclesiastical geography, Castel di Lucio sits at the westernmost end of the Roman Catholic Diocese of Patti.