2009–10 Football League One

The Football League 2009–10 (called Coca-Cola Football League for sponsorship reasons), was the seventeenth season under its current league division format. It began in August 2009 and ended on 8 May 2010.

The Football League is contested through three divisions. The second division of these is League One. Norwich City and Leeds United were automatically promoted to the Football League Championship as winners and runners-up respectively, and they were joined by the winner of the League One play-offs Millwall. The bottom four teams in the league were relegated to the third division, League Two.

From League One
Promoted to Championship
 * Leicester City
 * Peterborough United
 * Scunthorpe United

Relegated to League Two
 * Northampton Town
 * Crewe Alexandra
 * Cheltenham Town
 * Hereford United

To League One
Relegated from Championship
 * Norwich City
 * Southampton
 * Charlton Athletic

Promoted from League Two
 * Brentford
 * Exeter City
 * Wycombe Wanderers
 * Gillingham

Second leg
''Charlton Athletic 3–3 Swindon Town on aggregate. Swindon Town win 5–4 on penalties.''

Millwall win 2–0 on aggregate.

Final
Millwall are promoted to the Football League Championship