Since 1987, Koen Cosaert has been teaching carillon, campanology and harmony at the Carillon School Jef Denyn. On 1 September 2010, he was appointed director of the school. He is also a visiting professor of carillon and campanology at the Saint-Petersburg State University.
Koen Cosaert obtained a degree in musicology from the University of Leuven, with a dissertation titled "Jef Denyn, wegbereider van een nieuwe beiaardkunst" (Jef Denyn, paving the way for a new form of carillon art). He also holds a laureate diploma from the Carillon School Jef Denyn. He also studied organ and violin at the Conservatory of Kortrijk.
He has contributed to various exhibitions, journals and publications on the topic of bells and carillons as a campanologist. He also lectures at conferences and study days in Belgium, the United States, Germany, Ireland, Russia and the Netherlands.
Koen Cosaert is the carillonneur of the Belgian cities of Kortrijk, Roeselare, Harelbeke and Izegem. In 2011, he was awarded the Culture Trophy of the city of Roeselare for his work as an ambassador of carillon art.
Koen Cosaert has toured Europe and the United States and has given concerts at major music festivals such as the Festival of Flanders, the Happy New Festival (Kortrijk) and Oude Muziek Festival (Utrecht).