The Villans opened the scoring shortly before half time through Anwar El Ghazi's diving header from six yards out.
John McGinn added a second with an hour played following a goalkeeping error from Kelle Roos and, despite Jack Marriott pulling one back from the bench, Villa held on to seal their place in the top flight.
Relive how the 90 minutes of action unfolded with Sports Mole's live text coverage below.
The Villans, who lost in this showpiece fixture against Fulham 12 months ago, won both regular league meetings against today's opponents by a 7-0 aggregate scoreline.
Derby ended the season in better form, though, and they have plenty of momentum on their side after coming through an incredible semi-final against Leeds United 12 days ago.
There is £180m on the line for the winners of today's game. What will give in one of the biggest fixtures in the English footballing calendar? We are about to find out!
STARTING XI: Steer; Elmohamady, Tuanzebe, Mings, Taylor; Hourihane, McGinn; Adomah, Grealish, El Ghazi; Abraham
SUBS: Kalinic, Whelan, Jedinak, Lansbury, Kodjia, Hause, Green
STARTING XI: Roos; Bogle, Keogh, Tomori, Cole; Huddlestone, Johnson; Wilson, Mount, Lawrence; Bennett
SUBS: Carson, Waghorn, Jozefzoon, Marriott, Evans, McDonald, Knight
A couple of Jack Grealish corners caused some panic in the Derby box, but Axel Tuanzebe could not capitalise as he miscued his shot from seven yards after failing to properly adjust his feet.
Tammy Abraham turned in the area and curled a shot over and Mason Mount had a tame attempt from 25 yards smothered by Jed Steer as the game became more open.
There is still a long, long way to go at Wembley, though, and Derby know all about dramatic playoff comebacks. Here is a reminder of both sides' benches...
ASTON VILLA SUBS: Kalinic, Whelan, Jedinak, Lansbury, Kodjia, Hause, Green
DERBY SUBS: Carson, Waghorn, Jozefzoon, Marriott, Evans, McDonald, Knight
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Twelve months on from losing to Fulham here, the Villans held off a late Derby County onslaught to get over the line.
Anwar El Ghazi opened the scoring with a diving header just before half time and John McGinn added a second with an hour played. Despite Jack Marriott pulling one back from the bench, Villa held on for a famous victory.