Tomas Van Den Spiegel started as a 17 year old in the Belgian premier league. With his team Ostend, he became champion twice. They also concurred the cup twice. After playing in Italy (Fortitudo Bologna and Virtus Roma), he moved to CSKA Moskou. With this team, he won the EuroLeague in 2006 and 2008. In 2011, he returns to the Belgian competition in which he wins another two championships with Ostend.
He retired from basketball in 2013 and became president of the Union des Ligues Européennes de Basket (ULEB) in 2016.