Radonja is located in the municipality Vojnić, in Karlovac County at an elevation of 170 meters above sea level and it covers the area of 18.50 km² (7.14 sq. miles). According to the 2011 census report, there were 104 inhabitants. It is largely populated by Serbs (77%), but also Croats (23%). Nearby places: Jurga, Krivaja Vojnićka, Vojišnica, Vojnić, Radmanovac, Ključar, Kokirevo, Kolarić, Knežević Kosa and Kupljensko.