The Diocese of Osnabrück is a Latin Church ecclesiastical territory or diocese of the Catholic church in Germany. The diocese was originally founded circa 800. It should not be confused with the smaller Prince-Bishopric of Osnabrück–an ecclesiastical principality of the Holy Roman Empire until 1803–over which the bishop, as prince-bishop, exercised both temporal and spiritual authority.

The Prince-Bishopric of Osnabrück was an ecclesiastical principality of the Holy Roman Empire from 1225 until 1803. It should not be confused with the Diocese of Osnabrück, which was larger and over which the prince-bishop exercised only the spiritual authority of an ordinary bishop. It was named after its capital, Osnabrück.