In 1918 the town was controlled by Ukrainian People's Republic and the Ukrainian Hetmanate. From 1919 the town was controlled by Anton Denikin's White Armee of South Russia. In 1920, Ostrogozhsk became a part of Soviet Russia, while borders between the Soviet Russia and the Soviet Ukraine were not finalized until 1925. According to the census of 1926, ethnic Ukrainians accounted for 74.1 percent of the town's and 69.6 percent of the county's inhabitants. In 1928 Ostrogozhsk became a district's administrative center within what now is Voronezh Oblast. The town was occupied by Nazi Germany during World War II from July 5, 1942 (during the Battle of Voronezh) to January 20, 1943, when it was liberated in the course of the Ostrogozhsk–Rossosh Offensive.