The 1980–81 Southern Football League season was the 78th in the history of the league, an English football competition. Alvechurch won the Midland Division, whilst Dartford won the Southern Division. Alvechurch were declared Southern League champions after defeating Dartford 4–3 on penalties, after the two championship play-offs had finished 3–3 on aggregate (Alvechurch won 1–0 at home and Dartford won 3–2). Despite Alvechuch being champions, they declined promotion to the Alliance Premier League alongside Dartford as their board thought they were not ready, with third-placed Trowbridge Town going up in their place. There was no relegation for the second successive season, although Bognor Regis Town transferred to the Isthmian League at the end of the season.