In 1063, at the Synod of Jaca, under the auspices of King Ramiro I of Aragon and the presidency of the Archbishop of Auch, the ancient diocese of Huesca, whose seat was under Muslim Zaragozan control, was reestablished in the town of Jaca, which became "an instant city". Besides the archbishop of Auch, Austind, the synod was attended by other prelates of Gascony, Navarre and Aragon. Much of Jaca's early settlers were Gascons at this time. The synod determined the boundaries of the diocese, both present and future, that is, after its reconquista. Much of the new territory was taken at the expense of the diocese of Roda, whose bishop, Raymond, later litigated over Alquézar. It placed the canons of Jaca under the Augustinian Rule, and also introduced that rule into the royal chapels of Siresa, Loarre, Montearagón and Alquézar. Unspecified reform was introduced into the monasteries of San Juan de la Peña and San Victorián de Huesca, and the Roman rite replaced the old Visigothic liturgy. A new, eclectic cathedral, San Pedro Apóstol, was consecrated in Jaca.

The Diocese of Huesca is a Latin Church ecclesiastical territory or diocese of the Catholic Church located in north-eastern Spain, in the province of Huesca, part of the autonomous community of Aragón. The Diocese of Huesca is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Zaragoza.