The 2021 Banja Luka Challenger was a professional tennis tournament played on clay courts. It was the nineteenth edition of the tournament which was part of the 2021 ATP Challenger Tour. It took place in Banja Luka, Bosnia and Herzegovina from 6 to 12 September 2021.
Singles main-draw entrants
Seeds
1 Rankings are as of 30 August 2021.
Other entrants
The following players received wildcards into the singles main draw: Dražen Petrović Vladan Tadić Marko Topo
The following players received entry from the qualifying draw: Martín Cuevas Jonathan Mridha David Poljak Marko Tepavac
Champions
Singles
Juan Manuel Cerúndolo def. Nikola Milojević 6–3, 6–1.
Doubles
Antonio Šančić / Nino Serdarušić def. Ivan Sabanov / Matej Sabanov 6–3, 6–3.