First-half goals from Craig Bryson and Jamie Ward set Derby on their way to a first npower Championship victory since New Year's Day.
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Captain Richard Keogh added a third after half-time to inflict a first defeat on Huddersfield caretaker manager Mark Lillis - a former Rams player and coach.
It was Derby's first league win since beginning 2013 with a 3-1 success over Middlesbrough at Pride Park and keeps Nigel Clough's men hanging on to the coattails of the clubs in the play-off places.
The Rams were unchanged from the team that started last weekend's FA Cup defeat to Blackburn.
The only change on the bench saw leading goalscorer Theo Robinson return after illness, against his former club, in place of teenage striker Mason Bennett.
Lillis, in charge for the third time since Simon Grayson was sacked last week, also named an unchanged side following Town's first victory in 13 league matches against Crystal Palace on Wednesday night.
Derby dominated the first half, creating a handful of chances and thoroughly deserving their 2-0 lead at the interval.
Huddersfield goalkeeper Alex Smithies pushed Ward's 25-yard free-kick over the crossbar early on before another former Ram - James Vaughan -
burst into the box and curled a shot narrowly wide.
Oliver Norwood's long-range effort after 13 minutes had Adam Legzdins worried and the home goalkeeper, scrambling across his goal, would have been relieved to see the ball fly wide.
Thereafter though, it was all Derby. Conor Sammon's curler just missed the target before Bryson unleashed a 25-yard piledriver that marginally cleared the bar.
The Rams made the breakthrough in the 24th minute. Following a driving run down the right, Paul Coutts crossed the ball into the six-yard box where Bryson was on hand to tap in.
Only a last-ditch tackle by Peter Clarke, making his 400th league start, prevented Sammon from making it 2-0 after half an hour.
But three minutes later Derby did extend their lead when Gareth Roberts' cross was superbly volleyed into the top left-hand corner of the net by Ward.
John Brayford burst forward from right-back and almost scored a third goal but his effort went just wide.
The second half was relatively quiet, especially after the Rams scored their third goal and embarked upon long periods of keep-ball.
Keogh headed home Ward's free-kick after 59 minutes following Calum Woods' foul on Coutts.
Huddersfield nearly pulled a goal back in the 64th minute when Vaughan volleyed wide.
But Derby were still creating chances and Ward saw a goalbound effort blocked before Smithies denied Sammon with 15 minutes remaining.
Roberts worried the Town keeper late on with another long range effort but the left-back's shot whistled over the bar.