In a first half dominated by the home side it was former Miller Kevin Ellison who opened the scoring with a sweet counter attack on the half hour, latching onto Jack Redshaws through ball before powerfully firing past Andy Warrington.
Ellison, who appeared to gesture to the crowd in his celebration after receiving a warm reception before kick off, was later booked in the match.
Steve Evans' men saw shots blocked from Kari Arnason and Ben Pringle, while Alex Revell fired wide with the best chance of the half.
After the break though the game turned on his head just after the hour, as a fortunate deflection pinged the ball across the box for Nardiello to slot home at the far post and level the scores.
Then almost immediately Nardiello was on hand to turn home a low cross from the left after good work by Pringle and Bob Harris.
Minutes later the former Barnsley striker raced clear for his chance of the matchball, but his left footed shot went past the post with only Barry Roche to beat.
Morecambe offered little afterwards barring a small spell of late pressure, as Rotherham recorded back to back wins for the first time during Evans reign to move into the play-off pack.