A pupil of Hans von Koessler in Budapest, he taught at the Novi Sad High School, where he founded a music school and initiated the publication of the Serbian Music Magazine and the Serbian Music Library (an occasional edition of Serbian compositions). He was also interested in the melograph. He died in Novi Sad. His most important work is a romantic national opera Knez Ivo od Semberije (Prince Ivo of Semberia), based on folklore, the subject matter being from the Serbian Uprising against the Turks at the beginning of the 19th century.
In addition, he wrote a large number of plays and songs, and light operas as well, a symphony Miloš Obilić (which was lost), an overture Mena, piano pieces (Serbian Rhapsody, An Album of Compositions), songs with piano (the cycle Songs of Love), choral music, and music for tamburica bands.
Being romantically sentimental, melodically inventive, frequently almost identical with folk music, these works made him extremely popular within the region of his origin in his day. Also, many poems by Milorad M. Petrović (1875-1921) that were set to music by Isidor Bajić became classics in their own right (Po Gradini mesečina, Zarudela šljiva Ranka, Moj jablane, Sve dok je tvoga blagog oka, and others) more than a century later.