The Diocese of Luni was a Roman Catholic bishopric with its seat in Luni, Liguria, northwestern Italy. The bishop and cathedral chapter moved to Sarzana in the 12th century; the move was formalised in 1201. Though the bishops of Luni had been resident at Sarzana long before the official transfer of the cathedral, the diocese and bishop continued to use the name of Luni in their titles down to 1465, when the name of Sarzana was added to both. The name of the former diocese was revived in 1976 to designate a titular see.