The Bishopric of Leoben was a Roman Catholic diocese based in Leoben in Styria, Austria. The diocese covered the territory of the northern half of the state. It was created in 1786 by the Emperor Joseph II in his reforms of the church in Austria. After the death of its only bishop in 1800, the diocese was administered by the Cathedral chapter until 1808 and from then on the Bishops of Seckau. Already in 1804, plans were drawn to unite the bishopric with Seckau, although it occurred only in 1859 after the Pope finally agreed.