The 2009–10 3. Liga season was the second season for the newly formed tier III of the German football league system. The season began on 25 July 2009 and ended on 8 May 2010.
Third-placed team SC Paderborn 07 were also promoted after defeating the 16th-placed team from last year's 2nd Bundesliga, VfL Osnabrück, in a relegation playoff. As a result, Osnabrück would play in 3. Liga.
Exchange between 3. Liga and Regionalliga
VfR Aalen and Stuttgarter Kickers were relegated after finishing the 2008–09 season in the bottom two places. 18th-placed SV Wacker Burghausen were eventually spared from relegation after 5th-placed Kickers Emden voluntarily retracted their application for a license because of financial issues.[1] Emden will play in the fifth-tier Oberliga Niedersachsen.