Since 2009, Oskar Deecke has been a regular member of the German national hockey team. In that same year, the team won the silver medal in the European Championship in Amsterdam, Netherlands. At the 2010 World Cup Germany finished second, losing to Australia in the final. In 2011 Oskar Deecke and the German National Team won two titles: World Champion Indoor- Hockey in Poznan/ Poland, where he was one of the top scorers and European Champion in Mönchengladbach/ Germany. In 2012 his German National Team won two titles again: European Indoor Champion and they were the Gold Medalists at the 2012 Summer Olympics in London.. During the semi-finals against the Australian team on August 9. Deecke succeeded "The most spectacular goal of the tournament“ in the second half, as one reporter put it when he accepted a high ball from Benjamin Wess directly over the goalkeeper into the empty goal. Subsequently, this goal was disallowed after video evidence, because according to the former rules that the stick could not be passed over the shoulder. In 2013 he won with his team the European Championship, in 2015 he and his team reached second place.