| Mieczysław Biernacki | |
| Birth Date: | 30 March 1891 |
| Birth Place: | Lublin, Congress Poland |
| Death Place: | Lublin, Poland |
| Nationality: | Polish |
| Fields: | Mathematical chemistry |
| Workplaces: | Maria Curie-Skłodowska University |
| Alma Mater: | University of Paris |
| Doctoral Advisor: | Paul Montel |
| Doctoral Students: | Czesław Ryll-Nardzewski |
| Awards: | Stefan Banach Prize (1947) |
Mieczysław Kwiryn Biernacki (pronounced as /pl/; 30 March 1891 – 21 November 1959) was a Polish mathematical chemist.[1] He fought in World War I in the French Army and later in the forces of Polish general Józef Haller.