Österreichisches Museum für Kunst und Industrie (today the Museum für angewandte Kunst) in Vienna, where he met Giovanni Morelli and became interested in his theories of connoisseurship.
In 1895 Wickhoff published his major work, Die Wiener Genesis, a study of the development of Roman art from the time of Augustus to that of Constantine I.
Wickhoff's study would prove to be of great importance for the later Spätrömische Kunstindustrie of Alois Riegl, his younger contemporary at the Museum, which continued the project of rehabilitating late antique art.
It also sparked the extended feud between Riegl and Wickhoff, on the one side, and Josef Strzygowski, on the other, concerning the origins of the late antique style.
His students included many of the major figures of the next generation of Viennese art history, including Max Dvořák, Walter Friedländer, Wilhelm Koehler, Erica Tietze-Conrat, Hans Tietze and Gustav Glück.