The 30-year-old Serbian striker joined the Tabriz based club until the end of the season, reunited with his former coach Amir Ghalenoei.
Janjus won the Iran Professional League (IPL) title with Sepahan last season but fell out of favor with Croat coach Zlatko Kranjcar in the current season.
Janjus was a member of Pakhtakor Tashkent before joining Sepahan.