The 2008–09 Tercera División was the fourth tier of football in Spain.
Play started on 30 August 2008 and ended on 28 June 2009 with the promotion play-off finals.
The following clubs finished as champions of their respective groups The 18 group champion clubs participated in the Group winners promotion play-off and the losers from these 9 play-off ties then proceeded to the Non-champions promotion play-off with clubs finishing second, third and fourth.
de Torrelavega, Unión Estepona, Villajoyosa, Varea, Espanyol B, Real Oviedo, Toledo, Palencia and Compostela.
Promoted to Segunda División B: Izarra, San Roque, Alcalá, Cerro Reyes, Sporting Mahonés, Cacereño, Caravaca, Mallorca B and Mirandés.