Although he initially thought about becoming an actor, Jiří Fréhar ultimately obtained a degree in directing from the Theatre Faculty of the Academy of Performing Arts in 1967. Even during his studies he was an extra at the North Moravian Theatre in Šumperk. After completing university, he was a director at the Jaroslava Průcha Kladno-Mladá Boleslav Theatre, and at the Oldřich Stibor Theatre in Olomouc (where he later became the head of the drama section). At the end of the 1970s, he moved to Prague and was a director at the E. F. Burian Theatre. He later went to the Zdeněk Nejedlý Realistic Theatre, where he was also the theatre manager. In the 1990s, he directed productions at the Labyrint Theatre. Prior to his retirement, he returned to the theatre in Kladno, where he was engaged as the artistic director as well as a stage director.

Fréhar was also involved in educational activities, and he lectured at both the Theatre Faculty of the Academy of Performing Arts in Prague and the Professional Acting College. He is a member of the expert jury for the Thalia Awards in the drama category. He has directed over 160 productions.