The 2009–10 Liga II was the 70th season of the second tier of the Romanian football league system. The season started on 15 August 2009 and ended on 5 June 2010. The format has been maintained to two series, each of them consisting of 18 teams. At the end of the season, the top two teams of the series promoted to Liga I and the bottom fifth places from both series relegated to Liga III. Two more teams relegated this season due to the format changing applied starting with the next season.