It was New Mills that started off stronger, with striker Sam Cooke having an early effort that was well saved by Richard Stainsby, and whenever the visitors had the ball in the hosts' half they always looked a threat especially with Nathan Webb on the left-hand side.
However, it was Ilkeston that had the best opportunity of the half on 17 minutes when Reece Fyfe’s sweetly-struck low driven effort from 25 yards was only able to clip the outside of the post.
Six minutes later Daryl Mason had a chance for the visitors when he found himself in behind the Robbins' defence, but he was unable to beat Stainsby at the near post.
A few moments later Mason Lee found Massiah Macdonald free at the back post, but he couldn’t direct the ball towards the target when on the stretch.
The fixture burst into life in the second half when the Millers took a surprise but deserved lead.
Captain Darren McKnight’s low driven free-kick from 25 yards slipped under Stainsbys grasp allowing the ball to trickle into the bottom-left corner.
The home side did respond well to going behind as Dylan Forth made an excellent save to keep out Thomas Marshall’s header, and Jamie Walker had two opportunities in quick succession to level the game up.
In his first chance he couldn’t quite glance the ball on target as it floated just wide of the post, while his second chance was headed off the line.
After a couple of good chances, Ilkeston were unable to create any more clear-cut opportunities with the away side hitting them on the break on a number of occasions.
This pressure did eventually pay off when the Millers doubled their advantage on the 90 minute mark, when Nathan Webb's low effort giving Stainsby no chance.
Ilkeston did halve the deficit deep into stoppage time when substitute Alex Marshall bundled the ball home from a yard out after hitting the crossbar, but it wasn’t enough to see the game into penalties meaning that New Mills progressed into the quarter-finals of the Senior Challenge Cup.