He was one of the 144 deputies in the chamber who on 3 October 1990, as part of the German reunification process, became members of the Bundestag (National Assembly) of a reunited Germany. In the first post unification election, which took place in December 1990, Schwanitz's name was on the SPD list for the Saxony electoral district and to the Bundestag. He enjoyed electoral success in the Bundestag elections in 1994, 1998, 2002, 2005 and 2009, but did not contest a seat in 2013.