Rav Nosson Tzvi Finkel was born in Chicago, Illinois to Rabbi Eliyahu Meir Finkel and his wife, Sara Rosenblum, who ran a kosher catering business. His paternal grandfather, Rabbi Avraham Shmuel Finkel, was a "mashgiach ruchani" at the Hebron yeshiva in Israel, and his paternal great-grandfather was the Alter of Slabodka, Rabbi Nosson Tzvi Finkel, after whom he was named. He had one brother, Gedaliah, who now teaches at the Mir yeshiva. After his parents immigrated to Israel in 1973, his mother published a best-selling kosher cookbook.