Through his artistic and institutional reform efforts, he is credited with its revitalization and refinement, paving the way for new and significant Croatian musical achievements in the 20th century.

Zajc studied in Milan from 1850 to 1855, under the supervision of Stefano Ronchetti-Monteviti (counterpoint and composition), Alberto Mazzucato (orchestration), and Lauro Rossi (dramatic music).

Back home, he accepted the post of conductor and concert master of the Town Theatre Orchestra, taught stringed instruments at the Philharmonic Institute, and simultaneously wrote numerous compositions with his characteristic speed and ease.

Influenced by such Croatian cultural figures as bishop Josip Juraj Strossmayer and poets Petar Preradović, Ivan Trnski, August Šenoa, and Matija Divković, Zajc chose patriotism over world fame and returned to Croatia.

His efforts paved the way for new and significant Croatian musical achievements in the early 20th century, which Zajc himself lived to see up to his death on December 16, 1914 in Zagreb.