Vidarkinsky's term started on June 3, UniCredit Bank Banja Luka said in a press release.
Vidarkinsky is replacing Gordan Pehar, who resigned in April. Zeljko Kisic has served as interim president of the management board since then.
The lender's shares last traded on the Banja Luka stock exchange on March 26, when they closed 10.44% higher at 2,000 marka ($1,093/1,023 euro).
UniCredit Bank Banja Luka is based in the Serb Republic, one of two autonomous entities that form Bosnia and Herzegovina. UniCredit Group has another bank in Bosnia, UniCredit Bank Mostar, headquartered in the other entity - the Federation.
(1 euro = 1.956 marka)