Košutnjak (Кошутњак, kǒʃutɲaːk) is a park-forest and urban neighborhood of Belgrade, the capital of Serbia. It is divided between in the municipalities of Čukarica (upper and central parts) and Rakovica (lower part). With the adjoining Topčider, it is colloquially styled "Belgrade's oxygen factory". The 1923 Belgrade's general plan, in which one of the main projects regarding the green areas was forestation of the area between Topčider and the city, envisioned a continuous green area Senjak – Topčidersko Brdo – Hajd Park – Topčider – Košutnjak, which was formed by the 1930s. This continual forested area makes the largest "green massif" in the immediate vicinity of Belgrade's urban tissue.
The name, košutnjak, is derived from the medieval hunting forests of the Serbian nobility, meaning doe's breeder. (In Serbian, košuta means doe, hind), as does used to live freely in the park until the World War I. The name was mentioned for the first time in 1831.
The Košutnjak hill is high and the entire forest complex covers an area of .
Košutanjak has a few geological natural monuments. They include several Cretaceous maritime ridges of "Burdelj", "Tasin Majdan" and "Baremski", on the location of the assassination of the prince Michael, and a geology profile where the mint is located today.
Košutnjak is located 6 km southwest from the downtown Belgrade. It is bordered by the neighborhoods of Topčider to the north and west, Kanarevo Brdo to the northwest, Rakovica and Skojevsko Naselje to the south, and Žarkovo (with its extensions of Cerak, Cerak II, Repište) and Banovo Brdo (with its extension of Sunčana Padina) to the east. Filmski Grad (to the southwest) and Golf Naselje (to the northwest) are sub-neighborhoods of Košutnjak.
In the 19th century, Košutnjak was a fenced hunting ground and royal excursion place for the members of the Obrenović dynasty. Engineer, urbanist and professor at the Belgrade Lyceum, Atanasije Nikolić, was given a task of arranging the forest.