Banak represented Poland at the 2012 Summer Olympics in London, where he competed in the men's 120 kg class. He defeated Tunisia's Radhouane Chebbi in the preliminary round of sixteen, before losing out the quarterfinal match to Estonia's Heiki Nabi, who was able to score one point each in two straight periods, leaving Banak without a single point. Because his opponent advanced further into the final match, Banak had another shot for the bronze medal by entering the repechage bouts. Unfortunately, he was defeated in the first round by Belarus' Ioseb Chugoshvili, with a technical score of 0–3.