Mizanbaev B. began his service in the prosecutor's office in 2004 as an assistant prosecutor of the Saryarka district of Astana. Successively held various positions in the Metropolitan Prosecutor's Office and the Department of the Prosecutor General's Office.

In particular, he was the deputy prosecutor of the Yesil and Almaty districts, as well as the head of the Office for the Protection of Public Interests of the city prosecutor's office.

In April 2018, he was appointed the first prosecutor of the newly created Baikonyr district in the capital.

From June 2020 to June 2022, he served as Deputy Head of the Service for the Protection of Public Interests of the Prosecutor General's Office.

By order of the Prosecutor General dated June 27, 2022 No. 116, Mizanbaev B. was appointed Deputy Prosecutor of the city of Nur-Sultan. Since September 2022 - Deputy Prosecutor of the city of Astana.