The 1925–26 season was the 28th in the history of the Southern League.
The league consisted of Eastern and Western Divisions.
[1] Millwall II won the Eastern Division and Plymouth Argyle II won the Western Division.
Plymouth were declared Southern League champions after defeating Millwall 1–0 in a championship play-off.
The Western Division featured the same clubs as the previous season, minus the six clubs that had left.