In 1724 the Russians that were living in Ostrogozhsk, who were referred to as "people of posad" by the local inhabitants moved to Korotoyak and the Ukrainian Cossacks that lived in Korotoyak moved to Ostrogozhsk.[16]
The town served as the headquarters of a Sloboda Ukrainian Cossack territorial and military regiment until the 1760s when it was abolished by Catherine II.[17] In 1765 the city Ostrogozhsk was incorporated into newly established the Sloboda Ukraine Governorate.[11] In 1802 the city of Ostrogozhsk ended up in the new Voronezh Governorate[11] and same year it was granted the town rights. Since then the city became a center of the split East Sloboda Ukraine.
According to the 1897 Russian census there were 51,4% of Little Russians (Ukrainians) in the town of Ostogozhsk and 46,8% of Great Russians (Russians).[18] The inhabitants of the town continued to preserve their Ukrainian customs and Cossack traditions well into the twentieth century and their remains a district of the town named 'majdan'.[19]
In 1918 the town was controlled by Ukrainian People's Republic and the Ukrainian Hetmanate.[10] 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.[10] 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.[20] 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. The Germans operated a forced labour battalion for Jews in the town.[21]
^Всесоюзная перепись населения 1979 г. Национальный состав населения по регионам России [All Union Population Census of 1979. Ethnic composition of the population by regions of Russia] (XLS). Всесоюзная перепись населения 1979 года [All-Union Population Census of 1979] (in Russian). 1979 – via Demoscope Weekly (website of the Institute of Demographics of the State University—Higher School of Economics.
^"ОСТРОГОЗЬК". resource.history.org.ua. Retrieved March 13, 2020.
^Plokhy, Serhii (July 31, 2014). The Cossack myth : history and nationhood in the age of empires. Cambridge University Press. ISBN978-1-107-44903-9. OCLC1041371688.
Воронежская областная Дума. Закон №87-ОЗ от 27 октября 2006 г. «Об административно-территориальном устройстве Воронежской области и порядке его изменения», в ред. Закона №41-ОЗ от 13 апреля 2015 г. «О внесении изменений в Закон Воронежской области "Об административно-территориальном устройстве Воронежской области и порядке его изменения"». Вступил в силу по истечении 10 дней со дня официального опубликования. Опубликован: "Молодой коммунар", №123, 3 ноября 2006 г. (Voronezh Oblast Duma. Law #87-OZ of October 27, 2006 On the Administrative-Territorial Structure of Voronezh Oblast and on the Procedures of Changing It, as amended by the Law #41-OZ of April 13, 2015 On Amending the Law of Voronezh Oblast "On the Administrative-Territorial Structure of Voronezh Oblast and on the Procedures of Changing It". Effective as of after 10 days from the day of the official publication.).
Воронежская областная Дума. Закон №88-ОЗ от 2 декабря 2004 г. «Об установлении границ, наделении соответствующим статусом, определении административных центров муниципальных образований Грибановского, Каширского, Острогожского, Семилукского, Таловского, Хохольского районов и города Нововоронеж», в ред. Закона №77-ОЗ от 4 июня 2015 г. «О внесении изменений в отдельные законодательные акты Воронежской области в связи с изменением границ некоторых муниципальных образований Воронежской области». Вступил в силу со дня официального опубликования. Опубликован: "Коммуна", №189, 4 декабря 2004 г. (Voronezh Oblast Duma. Law #88-OZ of December 2, 2004 On Establishing the Borders, Granting Appropriate Status, Establishing the Administrative Centers of the Municipal Formations of Gribanovsky, Kashirsky, Ostrogozhsky, Semiluksky, Talovsky, Khokholsky Districts and the Town of Novovoronezh, as amended by the Law #77-OZ of June 4, 2015 On Amending Various Legislative Acts of Voronezh Oblast Due to Changing the Borders of Several Municipal Formations in Voronezh Oblast. Effective as of the official publication date.).