)[6] Kozelets Raion was located in the southwestern part of the Chernihiv Oblast,[7] corresponding to the modern-day boundaries of the Polissia historical regions.

To its west and south, it bordered upon Vyshhorod and Brovary Raions of Kyiv Oblast.

[7] As part of a full-scale administrative reorganization of the Ukrainian Soviet Socialist Republic, the Oster Raion was created on March 7, 1923, as an administrative entity of the Nizhyn Okruha; later in July of that year, the Kozelets Raion was also created.

Consequently, raions were subdivided into councils, which were the prime level of administrative division in the country.

Each of the raion's urban localities administered their own councils, often containing a few other villages within its jurisdiction.