Tommy Smith and Adam Bolder scored as Derby reached the Championship play-off places for the first time this season.
Inigo Idiakez hit the bar early on, but the Rams had to wait until 64 minutes to take the lead as Smith went round the Leeds defence before rifling home.
The victory was assured when substitute Bolder's 18-yard effort flew home after Neil Sullivan was wrong-footed by a deflection off Frazer Richardson.
David Healy wasted Leeds' best chance early on as he shot off-target.
Derby manager George Burley:
"The key thing is the lads have worked for each other all season.
"We kept a clean sheet tonight, and we didn't panic despite getting into so many good postions without managing to score in the first half.
"Tommy (Smith) is a quality player and a clever player, he sold about four dummies before he smacked it in the goal."
Leeds boss Kevin Blackwell:
"I think Derby are going to be dark horses for promotion this season because they've got experience in the right areas.
"I thought 2-0 was a little harsh as a scoreline, maybe 1-0 would have been about right because I think they just about shaded it overall.
"Ironically, we conceded during our best spell of the game when we were done by a goal we really should have prevented. And then we got mugged again for the second goal."
Derby: Camp, Kenna, Mills, Huddlestone, Jackson (Johnson 17), Bisgaard (Bolder 88), Taylor, Idiakez, Reich (Tudgay 80), Smith, Rasiak.
Subs Not Used: Grant, Junior.
Booked: Idiakez, Reich.
Goals: Smith 64, Bolder 90.
Leeds: Sullivan, Kelly, Carlisle, Butler, Richardson, Wright (Walton 75), Gregan, Pugh, Joachim (Griffit 65), Healy, Ricketts (Deane 69).
Subs Not Used: Harrison, Einarsson.
Booked: Ricketts, Gregan, Pugh.
Ref: P Taylor (Hertfordshire).