Boos began his career with the Düsseldorfer EG in 1992-93, becoming German champion in the first year. In 1994, he then switched to the Kassel Huskies, because he didn't get enough playing time in Düsseldorf. At the 1993 Under-18 European and the 1995 World Junior championship, however, he was one of the most important players for Germany. In 2000, he left Kassel and joined the Kölner Haie in Cologne. He has been the assistant captain for the Sharks since 2000.
Boos after the 06-07 season, was thinking about a move to an NHL team. With a pursuing contract, he looked to sign with the Buffalo Sabres or San Jose Sharks to be with fellow German player Marcel Goc but eventually stayed in Germany and plays the 07-08 season with the Hannover Scorpions.