Antoni Kazimierz Ostrowski (1713–1784) was a Polish priest and politician. He was bishop of Inflanty (1753–1763), bishop of Kujawy (1763–1776) and archbishop of Gniezno (also, Primate of Poland) (1777–1784). He was one of the Polish nobles in Russian service and supported their position, including presiding over the Partition Sejm in 1773–1775.

His Excellency Antoni Kazimierz Ostrowski
Archdiocese of Gniezno
Church	Roman Catholic
Archdiocese	Gniezno
Personal details
Born	31 March 1713 Ostrów
Died	28 August 1784
Nationality	Polish
Coat of arms

He was son of Ludwik Ostrowski and Katarzyna.