Guillaume Hoorickx played ice hockey for Belgium at the 1928 St. Moritz Winter Olympics. Little is known of his hockey career, as there are records only of the 1927/28 season when he played with Antwerpen CPA as a center. During World War II Hoorickx and his wife, Caroline, were part of the Red Orchestra, a Belgian resistance group, with Caroline assisting the Sukolov Group as a courier. Guillaume eventually became a prisoner at the Mauthausen-Gusen concentration camp in Austria, although he survived.