Halász began his musical career as principal bassoonist with the Philharmonia Hungarica in Vienna.
In 1978, Halász was appointed General Musical Director of the Hagen Philharmonic Orchestra [de], and in 1991 he was named Resident Conductor at the Vienna State Opera.
[3] Since 2011 he conducted every year at least one CD in Pardubice with the Czech Chamber Philharmonic Orchestra [cs] for Naxos.
[citation needed] Halász has made dozens of recordings for the Naxos and Marco Polo labels, ranging from the complete symphonies of Beethoven and Liszt's Symphonic poems to works by Mozart, Pergolesi, Dvorak, Mahler, Schubert and many others.
He has also recorded several of Mozart's operas, notably Don Giovanni, The Magic Flute, and The Marriage of Figaro.