Sahaidachnyi is a Ukrainian surname. It may refer to:
Petro Konashevych-Sahaidachny (c. 1582–1622), Ukrainian political, civic, and military leader Ukrainian frigate Hetman Sahaydachniy, a frigate of the Ukrainian Navy Hetman Petro Sahaidachnyi National Ground Forces Academy in Lviv, Ukraine Hetman Sahaidachny, a racing yacht