Bertels' programming was noticed for its eclectic mix of genres and artists, which pushed the Concertgebouw on the international stage with coproductions including Heiner Goebbels.
He was responsible for music programming and visual arts collaborations including projects with Devendra Banhart, Anohni, John Baldessari, Laurie Anderson and Mike Patton.
From 2010 to 2016 Lieven Bertels served on the board of directors of the International Society for the Performing Arts (ISPA) in New York.
His tenure brought a return to large-scale open-air installations including Florentijn Hofman's Giant Rubber Duck or Jeremy Deller's Sacrilege, alongside an expanded festival village in Sydney's Hyde Park which included Spiegeltents and outdoor entertainment.
His performing arts program included opera, contemporary dance and theatre and indie music from around the globe with artists including Rokia Traore, Peter Sellars, Thalia Theatre Hamburg, Vivienne Westwood, Anne Teresa De Keersmaeker, James Thierrée, Gotye, Joanna Newsom and The Flaming Lips.