Career
He made his debut in the professional football squad of Football Club Zwolle in the 2004-2005 season. He also played for Football Club Eindhoven before joining RKC Waalwijk. In 2007 Janssen was called up by Jong Oranje coach Foppe de Haan to be part of his squad for the 2007 Union of European Football Associations European Under-21 Football Championship where they qualified for the 2008 Summer Olympics.
At the 2007 Union of European Football Associations European Under-21 Championship, Janssen came on as a substitute and scored both penalties he took during the series (1–1, 13–12 after 32 penalty kicks) in the semi-finals against England.
The Dutch went on to retain their 2006 title by beating Serbia 4–1 in the final.