The 1909–10 season was the 16th in the history of Southern Football League.
Brighton & Hove Albion won Division One for the first time, Stoke and Hastings & St Leonards finished top of the Division Two groups, though they were not promoted to Division One.
[1] Stoke were the only club to apply for election to the Football League, but were unsuccessful.
A total of 22 teams contest the division, including 21 sides from previous season and one new team.
Stoke were the only Southern League club to apply for election to the Football League, but received only three votes.