Max Bird marked his Derby farewell with the opening goal in a 2-0 victory over Carlisle that sealed promotion back to the Championship.
It took only five minutes for the party to begin as Bird, who signed for Bristol City in January, celebrated his 200th and final Derby appearance by firing past Harry Lewis from 20 yards.
But already-relegated Carlisle showed they had not come to make up the numbers by putting Derby under pressure with Jack Armer forcing Joe Wildsmith into a save at his near post.
Ebou Adams thought he had scored in the 30th minute but the midfielder had strayed offside after Louie Sibley’s shot was blocked.
Derby looked edgy and Wildsmith tipped over a Georgie Kelly header to keep them ahead at half-time but the second goal they needed arrived in the 59th minute.
Wildsmith’s free-kick was headed down by Sonny Bradley and James Collins smashed in his 19th of the season from eight yards to spark wild celebrations at Pride Park.
