2019–20 Southern Counties East Football League Division One

At the end of season 2018–19, three teams left the division: The remaining 15 teams, together with the following, will form Division One for 2018–19:
 * Erith & Belvedere: promoted to the Premier Division
 * Phoenix Sports Reserves
 * Welling Town: promoted to the Premier Division
 * Croydon: relegated from the Premier Division
 * Rusthall: relegated from the Premier Division