He plays primarily as a Midfield. His preferred foot is Left. His current market value is estimated at 3M €.

His most recent move was a from Partizan Belgrade U19 to Partizan Belgrade on 2025-06-30.

Across 3 appearances in the UEFA European U19 Football Championship 2025-2026, B. Kostić registered 0 goals and 1 assists, while completing 0 key passes out of 0 total passes with a passing accuracy of -.