He made his debut for Germany on 29 September 2007 in a friendly against Switzerland. He made his last game for Germany to date against Portugal on 21 February 2009. He was also part of the squad for the Russia game on 2 May 2009 but was not substituted in.
In the 2008–09 season, while playing for the TSV Handschuhsheim, he was the top-scorer in the Bundesliga with 212 points. He joined the Heidelberger RK for the 2009–10 season but emigrated to Australia during the winter break.[2][3] He now plays for the Sunshine Coast Stingrays in Queensland Premier Rugby.[4]
After two years in Australia Wiedemann rejoined Heidelberger RK for the 2012-13 Bundesliga season.[5]