[1][2] Born in Berlin, Mahling studied musicology by Walter Gerstenberg, Georg Reichert, Joseph Müller-Blattau, and Walter Salmen at the University of Tübingen and the Saarland University (Saarbrücken) from 1957 to 1962.
(Dissertation: Studien zur Geschichte des Opernchors) and became assistant at the Musicological Institute of the Saarland University in 1963.
In 1972, he won his habilitation there with Walter Wiora for the subject Musicology (Habil.-Schrift: Orchester und Orchester-Musiker in Deutschland von 1700 bis 1850).
Since 1981 he had a professorship at the Johannes Gutenberg University Mainz; until March 2000 he was director of the musicological institute there.
Mahling also acted as one of the leading pioneers of a complete edition of the letters of Gaspare Spontini, which have been published by Hainholz Verlag [de] since 2013 in Göttingen.