Rotherham, though struggling at the opposite end of the table, had been in decent form themselves and gave the Canaries a scare or two in a relatively even match.
Goals from Kenny McLean and Ben Godfrey handed Norwich a victory which gave them a five point advantage over third-placed Leeds.
Joe Newell had the first effort on goal but Norwich goalkeeper Tim Krul was barely troubled by the midfielder's tame effort.
Rotherham then crafted a much better chance but Michael Smith guided his header over the bar, following swift interplay between Anthony Forde and Newell.
Norwich barely threatened in the opening 30 minutes before top-scorer Teemu Pukki reminded the Millers of his predatory prowess by sniffing out a half chance and firing just wide.
The away side managed to go in at the break in front thanks to McLean's goal in the 45th minute; the Scot slipped in behind the Rotherham defence from Pukki's pass and hooked the ball neatly beyond Marek Rodak.
It was the in-form Semi Ajayi who got the leveller for Rotherham, and his fifth in six games, in the 52nd minute as he turned and stroked in a curled effort from the edge of the box which beat the despairing Krul.
Pukki could have restored Norwich's lead almost instantly but he did not get enough of a connection on Max Aarons' centre and the ball flashed harmlessly wide of the far post.
Norwich did not have to wait much longer, though, with Godfrey putting them back ahead in the 57th minute. The defender held off his marker and met McLean's corner strongly and headed it back across goal into Rodak's far corner.
A chance opened up for Wiles from Smith's clever touch but the young midfielder blasted wide from 25 yards out. Emiliano Buendia then took aim from the edge of the box but his curling effort was just wide of goal.
Pukki had a much better chance to make the points secure. The Finn raced by Zak Vyner from the halfway line but could not force his shot past the onrushing Rodak on the angle.
Norwich could have made four minutes of additional time easier on themselves with another goal but Buendia's late shot was blocked.