He was the editor-in-chief of the weekly news magazine Der Spiegel from 1994 to February 2008 and has been the publisher of the conservative leading Die Welt newspaper since 2014 and the paper's editor until December 2016.

Two of Aust's books have been made into films: Der Pirat 1997 by Bernd Schadewald [de] and The Baader Meinhof Complex 2008 by Uli Edel.

"[9] In 2014, Aust became editor of the newspaper "Welt", which was published by Springer Verlag, which he fought against for decades.

Aust longtime defended the former Spiegel editor Matthias Matusek, which also switched 2013 to Welt and in 2015 get fired there, because he was drifting to the New Right and its German movement Neue Rechte.

[10] In 2010 Aust was awarded the Mercator Visiting Professorship for Political Management at the University of Duisburg-Essen's NRW School of Governance.