Kujnik is located in the municipality Brestovac, in Požega-Slavonia County at an elevation of 92 meters above sea level and it covers the area of 6.70 km² (2.59 sq. miles). According to the 2011 census report, there were 22 inhabitants. It is mostly populated by Serbs (63%), but also Croats (38%). Nearby places: Pasikovci, Orljavac, Crljenci, Sloboština, Podsreće, Rasna, Koprivna, Vranić, Deževci and Čečavac.