The 1948–49 Tercera División was the 13th edition of the Spanish national third tier.
14 clubs in 6 geographic groups (84 clubs) participated. One, Maestranza Aérea León withdrew mid-season. The 6 group champions and 6-runners up were promoted as of right. The 6 group champions played off for the Tercera División championship. The 6 third placed teams and the two bottom Segunda División teams played-off for two places in the Segunda División. In the event the play-offs were unnecessary since Segunda División was expanded from one division of 14 clubs to two divisions of 16 clubs for season 1949–50. No teams were relegated from Segunda División and the top 3 in all 6 groups were promoted.
This phase was canceled for the expansion of the Segunda División, all teams promoted.
This phase was canceled for the expansion of the Segunda División, all teams promoted.