This was about as comfortable as it gets for the Rams as they returned from a 17-day absence in style.
Rotherham are struggling at the bottom of the league but have been renowned for their hard work and fight despite their lowly position, often being hard to beat and having overcome the Rams on their own patch earlier in the campaign.
But Derby put any fears to bed in devastating fashion with a dominant and goal-filled display that delighted their supporters at a sunlit Pride Park, the like of which hasn't been seen over the course of a few weeks that have seen injuries and inconsistent displays hamper their momentum.
It was the first time Derby had scored six goals in a game since 1996 and the first time they've done it at Pride Park.
The break had clearly done Frank Lampard's men the power of good as a team but on an individual level, the returning Mason Mount pulled most of the strings and showed how badly he's been missed, Fikayo Tomori was immense at the back when called upon and hat-trick man Martyn Waghorn showed conviction when he had to with a morale-boosting display.
The game set the standard Lampard will no doubt expect his players to meet for the remaining eight games of the campaign, not that they'll be expected to score six in all of them.
Derby welcomed Mount back into the fray after a few weeks out and his presence was immediately felt as the Rams began brightly, much of their bright early play going through the Chelsea loanee in midfield.
Waghorn was blocked from shooting early on when the ball reached him in the penalty area, while at the other end Jerry Yates' low ball across the six yard box just evaded Ryan Williams who collided heavily with the far post and needed treatment, recovering sufficiently to drive a low shot wide of the post a couple of minutes later.
The Rams were then handed the chance to take the lead 12 minutes in when Mount turned in the penalty area and was fouled by Ben Wiles and Waghorn drove the spot kick low down the middle of the goal to put his side in front.
Harry Wilson then turned a Scott Malone cross over the top at the far post after another good Derby move, then Jayden Bogle's low ball into the six yard box only just evaded all interested parties as well as the goal itself.
Tom Lawrence jinked his way into space before firing into the side netting 20 minutes in as Derby continued to dominate, Bogle then mis-hitting a shot wide when fed by Duane Holmes moments later.
The Millers' most potent threat this season has been defender Semi Ajayi from set pieces, and their top scorer nearly turned in a corner on 28 minutes but a combination of keeper Kelle Roos and two Rams defenders only just kept the ball out of the net.
The second Rams goal eventually came on 39 minutes as a free-kick out wide found its way to Malone whose superb cross was headed down and in by Bradley Johnson from around ten yards out.
And two minutes later it was three. The ball was worked out to Holmes on the right and his cross was flicked home by Waghorn for his second goal of the afternoon to end the game as a contest before the break.
Roos was still called upon in stoppage time to palm away a curling Joe Newell free-kick, but the break arrived with the hosts firmly in control.
That position was strengthened within three minutes of the re-start. Derby worked the ball well down the right and Bogle's pull back was met by Mount who finished low into the corner of the net from just outside the six yard box.
Wilson then cut inside but saw his shot parried by keeper Marek Rodak and Rotherham cleared, before the visitors pulled one back on 54 minutes as Newell's left wing corner was powerfully headed home by skipper Richard Wood.
But the four-goal lead was restored eight minutes later as Wilson's cross was headed down by Mount, who may have been aiming for goal, and Holmes was able to turn the ball home from close range.
The Millers replied with Newell's deft chip coming back off the crossbar as they sought another consolation goal, but moments later it would be the Rams again to hit the net.
Lawrence was brought down by Rodak as he tried to go around him near the byline, and Waghorn stepped up to get his hat-trick goal and second from the spot.
The Rams eased off after that, two free-kicks from Wilson flying too high in the closing minutes, but their work was more than done.
Derby: Roos, Tomori, Keogh (c), Wilson, Mount (Bennett 76), Waghorn (Marriott 81), Lawrence, Johnson, Holmes, Bogle, Malone (Cole 76)
Subs not used: Carson, Wisdom, Bryson, Marriott, Huddlestone
Rotherham: Rodak, Vyner, Ajayi, Wood (c), Taylor (Towell 46), Iheikwe, Yates (Forde 78), Newell, Williams, Wiles (Crooks 46), Jones
Subs not used: Price, Palmer, Smith, Kayode
Ref: Tim Robinson
Derby - Waghorn 12pen, 42, 71pen, Johnson 39, Mount 48, Holmes 62
Rotherham - Wood 54
Star Ram: Mason Mount