Mladen Bašić studied piano, conducting and composition in the Zagreb Conservatory.
A year later he was employed as main conductor for the Mozarteum Orchestra of Salzburg.
From 1962 to 1972 he was permanent invited conductor in the Gran Teatre del Liceu of Barcelona.
From 1970 to 1978 he was the permanent director and programming supervisor of the Zagreb Philharmonic Orchestra, where he had a cooperation with the main conductor of that time, Lovro von Matačić.
He also performed many premieres of Croatian contemporary composers, such as the premiere of Boris Papandopulo's dramatic oratorio Marulova pisan, and first performances in his country of the best known works of Maurice Ravel, Benjamin Britten, Sergei Prokofiev, Igor Stravinski, Florent Schmitt and Béla Bartók.