Slomiansky was born in Ramat Gan during the Mandate era in the family, who migrated from the Second Polish Republic. He was educated at Bnei Akiva 's yeshiva in Nechalim, and completed academic studies in physics and mathematics at Bar-Ilan University. He also studied in the Hesder Yeshivat Kerem B'Yavneh, where he was certified as a teacher and ordained as a Rabbi. After his studies, he enlisted to the Nahal Paratroopers unit and reached the rank of first lieutenant. Thereafter, he turned to politics, serving for more than two decades (1977-1998) as the first head of Elkana local council. He was also the secretary-general of Gush Emunim.