The Diocese of Bosa was a Roman Catholic diocese in Sardinia that was founded in 1612 and merged into the diocese of Alghero-Bosa in 1986. It is asserted by some that the see was originally at , but was transferred to Bosa after the destruction of the former town; also, that the first bishop was Saint Emilius, sent thither by Saint Peter and martyred in 70 AD but there is no historical evidence.