Mario Haas started his career with SK Sturm Graz. This is also the club he played for most of the time during his professional career. Till 1999 he played for Sturm and was together with Ivica Vastic and Hannes Reinmayr part of the so called "magic triangel". He won two championships during this years. From here he went to the French club Racing Straßbourg, but was not successful. So he went back to Sturm. 2005 he went, together with his coach Ivica Osim to JEF United in the Japanese J-League. 2007 he came again back to Graz and played for SK Sturm.