Koch started his World Cup career in 1999 and finished in the top 3 in all ski jumping events eighteen times. This included two victories with the first being on 8 January 2011 in Harrachov. He also won a silver medal at the 2008 Ski Flying World Championships and six gold medals in team events at the 2006 Winter Olympics and World Championships. He made his last World Cup jump on 22 March 2014 on the large hill in Planica.