The Diocese of Sigüenza-Guadalajara (Latin: Dioecesis Seguntinus-Guadalaiarensis) is a Latin Church diocese of the Catholic Church located in the cities of Sigüenza and Guadalajara, Spain in the ecclesiastical province of Toledo in Spain. It is in the located in the secular Spanish province of Guadalajara in Castile, central Spain. It is bounded on the north by Soria, on the east by Zaragoza and Teruel, on the south by Cuenca and on the west by Guadalajara and Segovia.