From 1876 to 1880, he read German studies in Munich and Berlin and received his doctorate in 1881 in Strasbourg with the topic "Das Hrabanische Glossar und die ältesten Bayrischen Sprachdenkmäler.

[1] From 1887, he studied voice (with Benno Stolzenberg), composition (with Gustav Jensen) and piano (with Otto Klauwell [de]) at the Hochschule für Musik und Tanz Köln.

In one of his first appearances as a concert singer, he sang the tenor part in Beethoven's Ninth Symphony with the Gürzenich Orchestra Cologne conducted by his father in 1888.

[2] Wüllner was particularly known as a Lieder singer, collaborating with some of the most important musicians and composers of their time, such as Johannes Brahms, Richard Strauss, Fritz Steinbach, Arthur Nikisch, Hermann Zilcher, Artur Schnabel and Felix Weingartner.

[5] Successful concert tours took him to England, where he performed in 1903 in London and Manchester,[2] to the Netherlands, France,[6] Scandinavia, Russia, the UK and the U.S.[2] Elgar dedicated his "The Wind at Dawn" to him in 1907.