Danny Hylton's hat-trick saw Aldershot reach the FA Cup fourth round for the first time since the club reformed in 1992 with victory over Rotherham.
The striker was in fine form, scoring with a close-range effort, a header and a low drive to put the hosts 3-0 up.
Lee Frecklington did pull one back for the Millers from the penalty spot after Shots defender Ben Herd handled.
Both sides finished with 10 men, away defender Kari Arnason seeing red before Hylton was sent off shortly after.
Arnason's red was for a second bookable offence while Hylton was dismissed for an alleged elbow on Jason Taylor.
VIEW FROM THE DRESSING ROOM
Aldershot Town manager Dean Holdsworth told BBC Surrey:
"It's not just about the performance it's the way we went about our business today, the preparation was vital for us.
"The players are playing with confidence and that showed today.
"You don't beat Rotherham without playing with confidence, passion and desire and we've had all that today.
"We're playing against some very good players and you know they are going to give their manager everything and we needed to be exactly the same and we did today."
Aldershot Town 21 Young 02 Herd 03 Tonkin Booked 04 Morris 05 Brown 11 Vincenti 23 Bradley 39 Hector 28 Cadogan (Mekki - 83' ) 31 Rose 10 Hylton Dismissed Substitutes 29 Morris 16 Berqvrst 17 Mekki 33 Roberts 09 Rankine 14 Sinclair 20 Reid Rotherham United 21 Warrington 06 Mullins 34 O'Connell 04 Arnason Dismissed after an earlier booking 08 Taylor 10 O'Connor (Morgan - 46' ) 14 Bradley 15 Pringle 27 Frecklington 09 Revell (Odejayi - 60' ) 17 Nardiello (Cameron - 46' ) Substitutes 30 Thompson 05 Sharps 31 Cameron 32 Walker 11 Morgan 16 Odejayi 22 Agard