Born in Morocco, Ohayon immigrated to Israel with his family in 1956. He studied at a high school in Beersheba before joining the IDF for his national service. He went onto study at Bar-Ilan University, where he became chairman of the Student Association. After university he worked for the Jewish Agency in the United States, where he was responsible for encouraging students to study at Israeli universities. In 1979 he returned to Israel and joined the Education faculty at Bar-Ilan University, eventually becoming its deputy director. He also served as chairman of the Moroccan Immigrants' Organisation.