Radonja Luka is located in the municipality Sunja, in Sisak-Moslavina County at an elevation of 109 meters above sea level and it covers the area of 4.42 km² (1.71 sq. miles). According to the 2011 census report, there were 29 inhabitants. It is relatively populated by Croats (50%), but also Serbs (50%). Nearby places: Četvrtkovac, Donji Hrastovac, Gornji Hrastovac, Malo Krčevo, Vedro Polje, Drljača, Veliko Krčevo, Svinica, Mala Paukova and Staza.