His senior thesis, winner of both the Theron Rockwell Field Prize and Wrexham Prize and published in German by Suhrkamp Verlag in 1983 with the title Die Suche nach dem Labyrinth ("In Quest of the Labyrinth"), treated the myth of Daedalus and Icarus from Ancient Greek art and literature through James Joyce, with chapters on Ben Jonson, John Milton, and John Keats.

On a one-year fellowship from the Deutscher Akademischer Austauschdienst (1982–1983) to Heidelberg University, he worked on Martin Heidegger's interpretations of Friedrich Hölderlin, studying philosophy and German literature with Hans-Georg Gadamer and Peter Pfaff.

During this period, Koerner was also a member of the research group Poetik und Hermeneutik in Konstanz in its later phase, 1987–1994, writing on the themes of festival and contingency, or accident.

Subsequently, he curated "Earth Tidings," a collaboration between the ZKM and the Staatliche Kunsthalle Karlsruhe, in conjunction with Latour and Weibel's 2020-21 exhibition "Critical Zones."

Work on his father's art prompted an autobiographical turn, first exemplified in lectures delivered widely in the mid-1990s and captured in video "The Family Portrait"[2].

He has also written and taught on modern and contemporary artists, including Lucian Freud, Francesco Clemente, Vivienne Koorland, Luc Tuymans, and, most extensively, William Kentridge.

He has also published over seventy scholarly articles, including in Critical Inquiry, Representations, October (journal), Word & Image, and The Art Bulletin, where he was Book Review Editor in the early 1990s.

A book of this title on Bosch, Max Beckmann, Kentridge, with an introduction on Aby Warburg was released February 4, 2025 by Princeton University Press.

Pioneering "a way out of the monograph," this framework accords with his conception of the work of art as "inherently doubled," at once embedded in its historical context and anticipating its later receptions.

He received a Guggenheim Fellowship for his research on Reformation art (2006-7) and has served as visiting professor at the University of Konstanz (1991) and the Kunsthistorisches Institut in Florenz.

In 2009, Koerner was one of three recipients of the Andrew W. Mellon Foundation's Distinguished Achievement Award, which funded an academic and creative project on homemaking (geographic, architectural, and psychic) in Vienna from Otto Wagner to the present day.