Former Millers loanee Josh Koroma and Sorba Thomas scored the goals as Huddersfield made it back-to-back Sky Bet Championship victories with a 2-0 Yorkshire derby win over Rotherham.
Thomas made the first goal for Koroma before capping an inspirational display with a goal of his own to put the game to bed 20 minutes from the end.
The Millers are still searching for a first away win this season as Neil Warnock got the better of his former employers at The John Smith's Stadium.
Both sides started brightly and it was the home side who struck first inside 18 minutes with the game's first shot on target.
An inviting Thomas delivery wreaked havoc in the Rotherham defence and Koroma capitalised, converting first time on the volley.
The Millers responded positively as they searched for a quick equaliser, but Matty Pearson's crucial intervention preserved Town's slender lead.
A bright half by the hosts nearly improved when Ben Wiles' enticing cross was flicked inadvertently by Delano Burgzorg out of the waiting Thomas' path.
The dangerous Koroma then threatened to double his account for the afternoon, only to see his swerving strike held well by stopper Viktor Johansson.
Huddersfield should have increased their advantage shortly before the interval, but Wiles - who joined from Rotherham last month - scuppered a golden chance.
Burgzorg advanced purposefully and his pinpoint pull-back found the onrushing Wiles, only for the Terriers' new recruit to fire his effort wide.
Matt Taylor's half-time instructions nearly prompted an instant impact as Fred Onyedima's flicked header drew an impressive reflex stop from Lee Nicholls.
But Rotherham's bright start to the second period proved short-lived as Huddersfield gradually began to flex their attacking muscle in the final third.
First, the tenacious Wiles dispossessed Oliver Rathbone in a dangerous position, but the Millers' midfielder reacted quickly with an important block.
The hosts' strike partnership of Burgzorg and Kian Harratt then wasted two glorious opportunities in quick succession to double their advantage.
The former - a summer loan arrival from Mainz - dragged a strike well wide, while the latter - making his first league start - could not convert on the volley.
However, their combined blushes were soon saved when roles were reversed as goalscorer Koroma repaid Thomas' favour for Huddersfield's second.
A piercing counter ended with Koroma delivering a precise ball to find the onrushing Thomas, who slotted home from close range.
Substitute Tom Eaves had a gilt-edge chance to halve Rotherham's arrears, but he sent his free header straight at Nicholls in what summarised a dismal afternoon.