Hergüner was born in 1957 and graduated from Kadıköy Maarif High School. Having received his bachelor’s degree from Istanbul University Faculty of Law in 1979, he started his graduate studies in international public law at the same institution. After the second master’s degree at American University, where he went on a Fulbright scholarship in 1983, he earned his third one at Virginia University. During this period, he worked as a foreign legal advisor in the New York office of the Reid & Priest law firm. Hergüner, who taught at Istanbul University, Marmara University and Koç University after the second half of the 1980s, is a member of the Istanbul Bar and the American Bar Association. He is the founding partner of Hergüner Bilgen Özeke Attorney Partnership since 1989.