Marcelo Bielsa's side secured promotion to the Premier League and the league crown before even kicking a ball at Pride Park thanks to losses for both second-placed West Bromwich Albion and third-placed Brentford on Saturday and Sunday respectively (AEST).
It ends a 16-year wait to return to England's top flight for the Whites, who were relegated in 2004.
Leeds was given a guard of honour as it walked on to the pitch by the Rams, a mark of respect for its efforts all season.
When play began, it was clear there was little to play for as both sides produced few chances and looked a little lost throughout a lacklustre first half.
Nine minutes into the second half, the game appeared to crack open, Chris Martin scoring with a deflected shot to put Derby ahead before Pablo Hernandez netted in similar fashion two minutes later to level matters.
But the match began to drift again before Leeds took a firmer grip when Jamie Shackleton finished a slick move in the 75th minute. With just six minutes left of normal time, the visitors were gifted a third when Matthew Clarke sliced into his own net in calamitous fashion.
The Championship wraps up on Thursday (AEST) with the final round of fixtures. Leeds will play Charlton Athletic, which is still in some danger at the wrong end of the table, while Derby will travel to Birmingham City.