Lig due to sponsoring reasons) is the 47th season of the second-level football league of Turkey since its establishment in 1963–64.
2008–09 TFF First League champions Manisaspor, runners-up Diyarbakırspor and play-off winners Kasımpaşa were promoted to the 2009–10 Süper Lig.
They were replaced by Konyaspor, Kocaelispor and Hacettepe, who ended the 2008–09 season in the bottom three places of the standings.
They were replaced by Second League teams Bucaspor, Mersin İdmanyurdu and Çanakkale Dardanelspor.
The teams ranked third through sixth have competed in the promotion playoffs for the 2010–11 Süper Lig.