Four-goal Michael Chopra fired Cardiff back to form in a crushing victory.
Peter Whittingham got the first in an early sign that Derby's offside trap would be exposed, then he set up Chopra for his first strike since August.
Rob Hulse gave the Rams hope straight after the break, before the division's top-scorer Chopra took over, first latching on to Chris Burke's back-heel.
Stephen McPhail set up the hat-trick, a sweet chip, McPhail playing a part in Chris Burke's goal and Chopra's closer.
The Bluebirds had previously lost five of their last six matches in all competitions, an awful run that had seen the early season Championship leaders slip to ninth spot in the league.
But Derby provided the perfect opposition, having lost seven of their last nine away league games.
McPhail made a huge impression on his return from suspension, replacing Wales midfielder Joe Ledley who was banned for the game.
Peter Whittingham nets Cardiff's opener past Stephen Bywater
After 10 minutes the Irishman spotted Jay Bothroyd on a great run, the speedy striker beating the offside trap and finding Whittingham who netted his fifth of the season from close range.
The goal-scoring winger then turned provider with a long ball to Chopra, who made no mistake with a right-footed finish past Stephen Bywater to end his run of six games without a goal.
But the 18,670 home crowd - the first Cardiff attendance below 20,000 this season - were to endure some anxious moments.
Two minutes after the break, a weak Gavin Rae header from a defensive corner fell to Lee Hendrie.
Rob Hulse celebrates getting Derby back into the game at 2-1
Hulse battled with Mark Hudson to get on the end of the cross, the ball falling to the big Derby striker who toe-poked home.
After a nervy 10 minutes Rae made amends, heading to Burke who put a delightful back-heel flick into Chopra's path, the striker finishing coolly.
The Geordie completed his second hat-trick of the season just five minutes later, McPhail finding him on the edge of the box with a superb ball, Chopra lifting a sweet chip over Bywater with the inside of his foot.
A diagonal ball from McPhail then found Burke on the right, the wide man bursting into the box and unleashing a fierce finish past Bywater.
McPhail, making the 100th start of his career, was again provider as a memorable night was rounded off.
Chopra took the midfielder's pass on the outside of his boot and finished off the instep for his 12th goal of the season.
Cardiff manager Dave Jones: "Chopra's movement and finishing was top class and he showed us all what a good player he is.
"We had a lot of the ball and used it well but results like that don't come very often and we have to enjoy it while we can.
Jones basks in 'night to enjoy'
"Stephen McPhail came back into the side and was instrumental in at least three of the goals.
"When the team play like this they are superb but sometimes they switch off and perhaps that is why they are in this division.
"They are all good players and just because of one or two poor results it doesn't mean that they should be sent out of the club and new players brought in.
"We have to carry on working hard in training and it will be back to the grind [on Wednesday] because we have an important match on Saturday and one of our problems this season has been our inconsistency.
"If we can beat that then there is no reason why we cannot be a force in this division and we want to get out of it as quickly as possible."
Derby manager Nigel Clough:
"I am very disappointed at the way we let the goals in particularly after getting back into the game straight after half time.
"Cardiff were due a big win and Chopra some goals but it was a pity it had to come against us.
"We had some reasonable possession and should have done better but we are decimated by injuries and only had six players on the bench."
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