Before he was born, Kampl's parents moved from Maribor to Solingen, where he started his career with VfB Solingen. From 1997 he went on to Bayer 04 Leverkusen. In 2010 he signed his first contract. Because he did not play much he went on loan to SpVgg Greuther Fürth. After he came back he was still part of the squad but still played seldomly. He went to VfL Osnabrück in the 3rd league. The next club was VfR Aalen, where he only played two months. Then he signed for FC Red Bull Salzburg. It is said that Salzburg payed €3 million for Kampl. Within a short time he became an important player. In his first season he scored four goals and gave 9 assists.