A suppressed see in Lower Austria. Upon the request of Frederick III it was erected by Paul II on 14 January, 1469, and was immediately subject to the Holy See. At first it was coterminous with the town of Wiener-Neustadt, but in 1769 the new parish of Theresienfeld was added and in 1784 its territory was extended from Wiener-Neustadt to the boundary of Styria. On 21 April, 1785, the see was incorporated in the Archdiocese of Vienna by Joseph II. Its last bishop, Heinrich Johann Kerens, S.J. (1775-85), and his cathedral chapter was transferred to the newly erected diocese of Sankt Pölten. Of the twenty-three bishops of Wiener-Neustadt the most noteworthy were: Melchior Klesl, also Bishop of Vienna and cardinal (1614-30); Leopold, Count von Kollonitsch (1670-85), later Bishop of Raab, and Christopher Royas von Spinola (1686-95).
WIEDERMANN, Beitrage zur Gesch. des Bis. Wiener-Neustadt, in Oesterreich, Vierteljahrsschrift fur kath. Theol. (Vienna, 1864-9).