Bartłomiej Kłusek made his international debut on September 12, 2009 at an FIS Cup in Štrbské Pleso , Slovakia , where he finished 40th. After further competitions in this category, he took part in a COC competition in Wisła , Poland, for the first time on October 2, 2010 . In this competition class he was able to score first points in the following competitions and finish his first season in 46th place overall. In the summer of 2011 he competed in several Grand Prix competitions and reached 62nd place in the overall ranking. In the following season he took part again in COC competitions until he made his World Cup debut on January 20, 2012 in a jumping in Zakopane , Poland . However, so far in the World Cup could never reach the second round and the points associated with it. On March 4, 2012, he secured third place in a COC competition in Predazzo and thus his only podium finish on the international stage.
In January 2014 he was used again in the World Cup in the jumping in Poland, but was again without points in Wisła and Zakopane. Even in Sapporo a week later, he failed to score first. As a result, he had to be satisfied with mediocre results in the Continental Cup for the time being. It wasn't until the beginning of winter 2014/15 that he reached the podium in second place in Engelberg . He then traveled with the national A team to the Austrian jumping competitions of the Four Hills Tournament 2014/15 . After he missed the qualification in Innsbruck , he succeeded in Bischofshofen . However, he got stuck in the first round. In summer 2015 he achieved seventh place in the Summer Grand Prix in Wisła. However, it remained his only point win, which brought him in the end to 56th place in the overall standings.