Mamczarz represented his country at the 2012 Summer Paralympics in London where he won a bronze medal in the high jump (T42). More medals followed in the IPC Athletics World Championships with a pair of bronze medals won in the high jump in 2013 in Lyon and 2015 in Doha. Mamczarz is also a double European Championships gold medalist, winning his event in both Swansea (2014) and Grosseto (2016).