Brighton were named champions of League One after their hard-fought victory at struggling Walsall.
Inigo Calderon, who scored in the win over Dagenham and Redbridge that sealed promotion on Tuesday, headed the visitors in front.
Andy Butler nodded in an equaliser, but the Seagulls' top-scorer Glenn Murray glanced in a header for 2-1.
The Saddlers' Emmanuel Ledesma saw red for fouling Adam El-Abd before Elliott Bennett lashed home from 30 yards.
Brighton, who are unbeaten at home so far this season, will return to the Championship after a five-year absence.
They do so on the back of a 12-game unbeaten run that stretches back until the end of February.
In stark contrast, Walsall remain in 20th position, level on points with Bristol Rovers in 21st and a point and a game ahead of Notts County in 22nd.
The final whistle was greeted with a pitch invasion by the travelling Brighton supporters.
Brighton manager Gus Poyet told BBC Sussex:
"It's unbelievable to be top and know that no one can go above us, we were the best team in this league by far.
"Elliot Bennett has the best shot and best delivery in the club and I'm so pleased for him today.
"It is a team effort and we told the players not to try and be a hero on your own, and today is about forgetting all worries and just celebrating."