Early work of Kerim Seiler is characterized by two-dimensional, life-size paintings of ordinary city objects, such as park benches and ticket machines.

[1] He diversified into larger works, such as colorful and inflatable molecule sculptures, a 250-meter-long permanent neon light installation at Zürich's central train station[2] and his vaguely habitable brick structure Gulliver in Pfungen (2009).

[9][10] Though his large-scale works often entail municipal (e.g., his 2014 building facade Iris in Schlieren, Switzerland[11][12][13]) or ecclesiastical (e.g., his prominent 2015 neon sculpture DIMETHYLTRYPTAMIN at the Roman Catholic Diocese / erstwhile Prince-Bishopric of Würzburg[14]) collaboration, they are sometimes executed covertly and/or via agricultural machinery.

[15]: 103 In 2016 Seiler created "a neon sign in the shape of bones",[16] and, according to Urs Bühler, a neon installation entitled "Space Knot" proceeding along 300 linear meters beneath the Swiss National Museum ceiling, "like a ghost presiding over the museum, curved shapes giving an impression of Harald Naegeli spray cans transubstantiated into colorful illumination.

[23] Seiler's work is exhibited worldwide, including in Moscow, Cairo, Zürich, New York City, Berlin, Paris, Los Angeles and Johannesburg.