Championship leaders Brighton were promoted to the Premier League after they beat relegation-threatened Wigan, and Huddersfield then drew at Derby.
Brighton had to wait on the result of the 17:00 BST kick-off at Pride Park, before their return to the top flight after 34 years was confirmed.
Glenn Murray’s crisp strike from the edge of the area put the hosts ahead.
Solly March smashed in a second after the break, before Nick Powell’s header made it a nervy final five minutes.
Brighton can now start preparing for life in the top division again following their relegation in 1982-83 and subsequent journey down and back up the leagues.
A Huddersfield win would have meant the Seagulls needed one more point to mathematically guarantee promotion, but their goal difference was already far superior to the Terriers.
Wigan put up a spirited defensive display but offered little going forward until Powell’s goal, and now face the prospect of an immediate return to League One.
They are five points from safety with three to play, including games against play-off chasing Reading and Leeds.