In 2004, he co-founded and leads Tribal Nova as co-CEO. Tribal Nova quickly became a major player in the field of publishing online channels for kids, virtual words, apps and educational games before being acquired by HMH in 2013.
Since 2018, Guillaume is acting as international and strategic development executive advisor for the Quartier des Spectacles Partnership. He also sits on the boards of prestigious organizations such as CBC/Radio-Canada, La Piscine-Rodier (creative companies accelerator) and the Printemps Numérique (Montreal Digital Spring Event) as President.