He scored his first goal in the German Field Hockey National League in 2003, just a few days before his 17th birthday.

Oskar Deecke started his international career in 2006, as part of the German Junior National Team that won a silver medal at the U21 European Championship in Prague, Czech Republic.

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.[3].

Deecke participated in the auction for the 2013 Hockey India League, where he was bought by the Delhi Waveriders franchise.

Wearing the number 7 shirt, Deecke was an integral part of the team, scoring 4 goals (as of 10 Feb 2013), and having a hand in many others.