In March 2003, Śliż was in Szczyrk ahead of Janusz Zygmuntowicz and Daniel Bachleda Polish national champion in Nordic combined, where his strengths came to light in the jump. In the 2003/04 season, Śliż moved to the camp of jumpers. At the Universiade 2005 in Innsbruck , the student took seventh place. In the 2005/06 season, Śliż finished eighth overall at the Continental Cup . Śliż took part in the 2006 Winter Olympics in Turin , where he could not qualify for the competition on the large hill. At the home World Cup in Zakopane he was able to jump on January 16, 2009 as thirteenth his best individual result. On March 10, 2010, Śliż succeeded in Kuusamo for the first time in over a year to win a Continental Cup competition, after having previously jumped to podium places several times. Also at the beginning of the 2010/11 season he achieved several good placements, so that he then took part in the qualification for a World Cup competition for the first time in Innsbruck in January 2011 as part of the Four Hills Tournament 2010/11 . In Bischofshofen he made the leap into the competition, where he finished 47th in the end. In Sapporo he was able to win World Cup points on January 16, 2011 for the first time since 2009. At the Polish championships in February 2011, he finished third behind Kamil Stoch and Tomasz Byrt in the individual. After taking part in the last competition at the FIS Cup in Zakopane in February 2014, Śliż declared his resignation.
Today Śliż lives in Wisła with his wife and child.