Burnley scored three times in 12 second-half minutes to go third in the Championship and extend Derby's winless period to five league games.
Derby's Richard Keogh headed Matt Lowton's cross into his own net on 29 minutes but Jacob Butterfield replied with a 20-yard volley within a minute.
Andre Gray and Sam Vokes both scored penalties before Scott Arfield's shot deflected in off Jason Shackell.
Burnley trail Middlesbrough in second by four points, with Derby fifth.
Relive Burnley's 4-1 win over Derby
The Rams have taken only two points from their last five league games, although they perhaps did not deserve to lose by such a hefty margin to one of their main rivals for automatic promotion.
Chris Martin and Tom Ince forced saves from Burnley goalkeeper Tom Heaton before Keogh's own goal, and they had another good period of pressure after Butterfield's well-taken equaliser.
However, they were undone by a period of poor defending which saw them concede two penalties in four minutes after half-time.
Clement on Burnley v Derby
Keogh tripped Gray who was jinking inside the six-yard box, allowing the Championship's leading scorer to net his 17th goal of the season, before ex-Burnley captain Shackell handled a right-wing cross and Vokes duly converted the resulting spot-kick.
On his return to Turf Moor, Shackell's evening was made worse when Arfield's low effort looped off his foot and over Scott Carson into the net.
While Derby are faltering, the Clarets are growing into genuine top-two contenders. Their manager Sean Dyche was able to select an unchanged starting line-up for the fifth game in a row, while they have scored 12 goals and let in just two during a three-game winning sequence in the Championship.
Burnley manager Sean Dyche: "We have to stay strong now. Some of our football was excellent in the second half, there was some real quality out there.
"Don't forget Derby are a very good side, but I'm delighted because now we've started scoring from all over the pitch and that does make a difference.
"Margins are tight at the top of the division, but we just have to keep working hard and keep scoring like that."
Derby head coach Paul Clement: "Things were looking positive at half-time, but that four or five-minute period in the second half proved costly for us.
"I'm not an idiot, though. We've lost 4-1 and we have to do better.
"That's been the difference - what happened in the two penalty areas. They defended theirs well and we didn't. I've no complaints about the penalty decisions.
"It's just been a night to forget."
Lineup, Bookings (2) & Substitutions (5)
Burnley
- 01 Heaton
- 02 Lowton
- 05 Keane
- 06 Mee
- 23 Ward
- 21 Boyd
- 14 Jones
- 13 Barton
- 37 Arfield
- 09 Vokes (Marney - 89' )
- 07 Gray (Hennings - 79' )
Substitutes
- 04 Duff
- 08 Marney
- 11 Kightly
- 15 Taylor
- 18 Hennings
- 27 Darikwa
- 40 Nizic
Derby County
- 17 Carson
- 02 Christie
- 06 Keogh
- 14 Shackell Booked
- 37 Warnock
- 18 Butterfield
- 34 Thorne
- 15 Johnson Booked (Camara - 69' )
- 23 Ince (Russell - 79' )
- 09 Martin
- 22 Blackman (Bryson - 86' )
Substitutes
- 01 Grant
- 04 Bryson
- 08 Hendrick
- 11 Russell
- 12 Baird
- 20 Camara
- 32 Shotton
Match Stats
Live Text Commentary
Full Time Match ends, Burnley 4, Derby County 1.
90:00 +3:06 Full timeFull Time Second Half ends, Burnley 4, Derby County 1.
90:00 +2:33Stephen Warnock (Derby County) wins a free kick in the attacking half.
90:00 +2:33Foul by Joey Barton (Burnley).
90:00 +1:54Attempt blocked. Chris Martin (Derby County) left footed shot from the centre of the box is blocked. Assisted by Cyrus Christie.
90:00 +1:54Corner, Derby County. Conceded by Michael Keane.
90:00 +1:17Corner, Derby County. Conceded by Ben Mee.
89:23Foul by George Thorne (Derby County).
89:23Joey Barton (Burnley) wins a free kick in the defensive half.
88:08 SubstitutionSubstitution Substitution, Burnley. Dean Marney replaces Sam Vokes.
85:54 SubstitutionSubstitution Substitution, Derby County. Craig Bryson replaces Nick Blackman.
80:28Foul by George Thorne (Derby County).
80:28Rouwen Hennings (Burnley) wins a free kick on the left wing.
78:28Delay over. They are ready to continue.
78:26 SubstitutionSubstitution Substitution, Burnley. Rouwen Hennings replaces Andre Gray because of an injury.
78:01 SubstitutionSubstitution Substitution, Derby County. Johnny Russell replaces Tom Ince.
77:19Delay in match Andre Gray (Burnley) because of an injury.
76:54Attempt missed. Andre Gray (Burnley) right footed shot from more than 35 yards misses to the right.
75:40Attempt saved. David Jones (Burnley) left footed shot from outside the box is saved in the centre of the goal. Assisted by Sam Vokes.
73:27Corner, Burnley. Conceded by Scott Carson.
Attempt saved. Andre Gray (Burnley) right footed shot from outside the box is saved in the bottom right corner. Assisted by George Boyd.
72:16Attempt missed. Tom Ince (Derby County) right footed shot from the right side of the box misses to the left. Assisted by George Thorne.
70:35Corner, Derby County. Conceded by Matthew Lowton.
69:05George Thorne (Derby County) wins a free kick in the defensive half.
69:05Foul by Joey Barton (Burnley).
68:02 SubstitutionSubstitution Substitution, Derby County. Abdoul Camara replaces Bradley Johnson.
67:31 BookingBooking Bradley Johnson (Derby County) is shown the yellow card for a bad foul.
67:05Foul by Bradley Johnson (Derby County).
67:05Joey Barton (Burnley) wins a free kick in the defensive half.
65:27 Goal scoredGoal! Goal! Burnley 4, Derby County 1. Scott Arfield (Burnley) right footed shot from outside the box to the centre of the goal. Assisted by Matthew Lowton.
63:41Stephen Warnock (Derby County) wins a free kick in the defensive half.
63:41Foul by Scott Arfield (Burnley).
63:12Attempt saved. Bradley Johnson (Derby County) left footed shot from outside the box is saved in the centre of the goal. Assisted by George Thorne.
61:57Hand ball by Bradley Johnson (Derby County).
60:16Bradley Johnson (Derby County) wins a free kick in the attacking half.
60:16Foul by Joey Barton (Burnley).
59:42Bradley Johnson (Derby County) wins a free kick in the defensive half.
59:42Foul by Matthew Lowton (Burnley).
57:29 Goal scoredGoal! Goal! Burnley 3, Derby County 1. Sam Vokes (Burnley) converts the penalty with a right footed shot to the centre of the goal.
56:51 BookingBooking Jason Shackell (Derby County) is shown the yellow card for hand ball.
56:30Penalty conceded by Jason Shackell (Derby County) with a hand ball in the penalty area.
53:50 Goal scoredGoal! Goal! Burnley 2, Derby County 1. Andre Gray (Burnley) converts the penalty with a right footed shot to the centre of the goal.
52:49Penalty conceded by Richard Keogh (Derby County) after a foul in the penalty area.
52:49Penalty Burnley. Andre Gray draws a foul in the penalty area.
51:38Corner, Derby County. Conceded by Michael Keane.
50:50Corner, Burnley. Conceded by Jason Shackell.
50:18Corner, Burnley. Conceded by Jason Shackell.
46:24Tom Ince (Derby County) wins a free kick in the defensive half.
46:24Foul by Stephen Ward (Burnley).
45:00Second Half begins Burnley 1, Derby County 1.
45:00 +1:06 Half timeHalf Time First Half ends, Burnley 1, Derby County 1.
45:00 +0:26Foul by Chris Martin (Derby County).
45:00 +0:26Ben Mee (Burnley) wins a free kick in the defensive half.
44:41Corner, Derby County. Conceded by Stephen Ward.
43:28Attempt blocked. Tom Ince (Derby County) left footed shot from outside the box is blocked. Assisted by Chris Martin with a headed pass.
39:49Attempt blocked. Jacob Butterfield (Derby County) left footed shot from outside the box is blocked.
38:23Attempt saved. Sam Vokes (Burnley) right footed shot from outside the box is saved in the centre of the goal. Assisted by Scott Arfield.
37:40Attempt blocked. Chris Martin (Derby County) right footed shot from the left side of the box is blocked. Assisted by Nick Blackman.
35:59Foul by Bradley Johnson (Derby County).
35:59Joey Barton (Burnley) wins a free kick in the defensive half.
34:37Chris Martin (Derby County) wins a free kick in the attacking half.
34:37Foul by Ben Mee (Burnley).
32:43Attempt missed. Nick Blackman (Derby County) left footed shot from the right side of the six yard box is high and wide to the left. Assisted by Chris Martin with a headed pass following a corner.
32:08Corner, Derby County. Conceded by George Boyd.
32:07Attempt blocked. Nick Blackman (Derby County) left footed shot from the left side of the box is blocked. Assisted by Cyrus Christie with a cross.
31:03Attempt missed. Andre Gray (Burnley) right footed shot from the centre of the box misses to the left. Assisted by Joey Barton.
29:20 Goal scoredGoal! Goal! Burnley 1, Derby County 1. Jacob Butterfield (Derby County) right footed shot from outside the box to the bottom right corner. Assisted by Chris Martin.
28:07 Goal scoredGoal! Own Goal by Richard Keogh, Derby County. Burnley 1, Derby County 0.
26:08Attempt missed. Scott Arfield (Burnley) right footed shot from outside the box is high and wide to the left.
25:26Foul by Cyrus Christie (Derby County).
25:26Stephen Ward (Burnley) wins a free kick on the left wing.
22:59Nick Blackman (Derby County) wins a free kick in the attacking half.
22:59Foul by Joey Barton (Burnley).
20:24Corner, Derby County. Conceded by Scott Arfield.
19:46George Thorne (Derby County) wins a free kick in the attacking half.
19:46Foul by Sam Vokes (Burnley).
18:25Hand ball by George Thorne (Derby County).
18:08Attempt missed. Jason Shackell (Derby County) header from the centre of the box is just a bit too high. Assisted by Cyrus Christie with a cross following a corner.
17:36Corner, Derby County. Conceded by Ben Mee.
17:11Attempt blocked. George Thorne (Derby County) right footed shot from outside the box is blocked. Assisted by Stephen Warnock.
16:55Corner, Derby County. Conceded by Andre Gray.
16:25Corner, Derby County. Conceded by Michael Keane.
12:53George Thorne (Derby County) wins a free kick in the defensive half.
12:53Foul by George Boyd (Burnley).
12:32Foul by Bradley Johnson (Derby County).
12:32Matthew Lowton (Burnley) wins a free kick in the defensive half.
10:34Attempt missed. George Thorne (Derby County) right footed shot from outside the box is high and wide to the right following a corner.
9:57Corner, Derby County. Conceded by Matthew Lowton.
8:02Attempt saved. Tom Ince (Derby County) left footed shot from outside the box is saved in the centre of the goal. Assisted by Jacob Butterfield.
2:22Foul by Andre Gray (Burnley).
2:22Jason Shackell (Derby County) wins a free kick in the defensive half.
1:24Attempt saved. Chris Martin (Derby County) right footed shot from the centre of the box is saved in the bottom right corner.
0:44Foul by Joey Barton (Burnley).
0:44Stephen Warnock (Derby County) wins a free kick on the left wing.
0:00First Half begins.
0:00Lineups are announced and players are warming up.
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