| Type: | cardinal |
| Honorific-Prefix: | His Eminence |
| Michał Stefan Radziejowski | |
| Cardinal, Primate of Poland | |
| Archdiocese: | Gniezno |
| See: | Archdiocese of Gniezno |
| Term Start: | 1688 |
| Term End: | 1705 |
| Consecration: | 26 January 1681 |
| Cardinal: | 1686 |
| Rank: | Cardinal-Priest |
| Coat Of Arms: | POL COA Junosza.svg |
| Birth Date: | 3 December 1645 |
| Birth Place: | Radziejowice |
| Death Date: | 13 October |
| Death Place: | Gdańsk |
| Nationality: | Polish |
| Religion: | Roman Catholic |
Augustyn Michał Stefan Radziejowski (3 December 1645 – 13 October 1705) was an archbishop of Gniezno and cardinal primate of the Roman Catholic Church in Poland,[1] son of Hieronim Radziejowski. After the death of the Polish king John III Sobieski, he functioned as Interrex until the choice of a new king.
Radziejowski first supported the candidacy of François Louis, Prince of Conti. Later he supported August II the Strong, the eventual successor to John III.
He died in Gdańsk (Danzig), 13 October 1705 due to old age.