Bristol City ended their six-year spell in the Championship with a 4-1 defeat at Charlton.
After a goal-less first half, Yann Kermorgant scored twice in four minutes for the hosts, before Bobby Reid pulled a goal back for City.
Former Yeovil Town loanee Jon Obika and Johnnie Jackson added further goals for the Addicks.
Sean O'Driscoll's men finished bottom of the table, and will be joined in League One by Wolves and Peterborough.
Exeter Chiefs beat West Country rivals Gloucester with the last kick of the match at Sandy Park. Bath lost 23-14 at Saracens.
Cheltenham Town move up to fourth in League Two after a 1-0 win at Exeter. There were also wins for Yeovil and Swindon in League One.
Yeovil Town and Cheltenham Town have both secured play-off places in their respective divisions after wins today.