Koen completed his film studies at RITS and in 1999 founded CZAR Brussels with fellow director Joe Vanhoutteghem.
Over the years, he has won numerous international awards, including 8 Lions at the 2012 Cannes Festival for his TNT Push to Add Drama. This highly acclaimed film won over 50 awards, reached over 60 million clicks, and is the most awarded Belgian campaign in history.
Koen’s Hornbach film And What Will Remain of You for the German market picked up numerous awards at international award festivals including Epica, New York Film Festival, ADC, Gold at The Golden Award of Montreux and Best Film at DWP.
Besides his successful advertising career, Mortier has also internationally toured with his feature films. His first four films all premiered at the Toronto International Film Festival. His first feature Ex Drummer (2007) also premiered at Rotterdam and won several international awards. His next film 22nd of May picked up awards at the Leeds, Mexico and Baghdad International Film Festivals. Un Ange (2018) also made the international film festival circuit. In 2022 Koen directed Voices Of Liberation an 11-part Netflix docu-series on World War II. In additional to multiple international awards, his most recent feature film Skunk (2023) won Best Film at Just Film, the youth sub-festival at the Tallinn Black Nights and the Best Film Award at the Ensors 2025. It was the most-watched Flemish film of 2024.
Under the alias Lionel Goldstein, Koen directs films with Joe Vanhoutteghem. Driven by their shared love of the absurd, they consistently push creative boundaries. Their work has earned widespread international acclaim, including five Gold Lions at Cannes—awarded for standout campaigns such as FRISK and XBOX (for Wieden+Kennedy London and BBH London, respectively), DEXIA Braille, Equal Pay Day Eternal Pregnancy, and most recently, Lynx The Robbery. In total, Lionel Goldstein has collected over 18 Cannes Lions as well as numerous other international awards for films such as Canal Digital, Hornbach, and Gent Filmfest 2023, to name a few.