Horga studied history at Babes Bolyai University in Cluj-Napoca, graduating in 1980 with the highest GPA of his class. He worked briefly as a high school teacher, before working for five years at the Directorate of the School of the Committee of the Union of Communist Youth in Bihor County. After the Romanian Revolution of 1989, he went back to work as a high school teacher until he joined the University of Oradea in 1993. In 1995 he obtained a doctorate in history from University of Reims Champagne-Ardenne, with a thesis on the Romanian Greek Catholic Church (United with Rome) of Transylvania during the Enlightenment Era: The episcopate of Oradea (1780-1830), under the supervision of Viviane Barrie-Curien. He thus became the first Romanian national to obtain a doctoral degree abroad after the 1989 Revolution.