The Royals took the lead after 22 minutes when Bobby Convey lashed home John Oster's pull-back.
But Wolves stunned the home fans when Miller capitalised on hesitancy inside the Reading box to slam a right-foot shot past Marcus Hahnemann.
Jeremie Aliadiere might even have snatched the win for Wolves but poked his shot over the bar from close range.
Wolves boss Glenn Hoddle:
"They are the side of the moment, and rightly so, but there wasn't anything between the two teams.
"From half-time onwards we could have caved in, but we stepped up a gear and they found it hard to keep with us, so credit to the lads.
"I thought the front men did well for us. Frankowski's all-round play has surprised me, as well as his general awareness."
Reading: Hahnemann, Murty, Shorey, Sonko, Ingimarsson, Oster (Hunt 88), Gunnarsson (Sidwell 76), Harper, Convey, Kitson, Doyle. Subs Not Used: Stack, Makin, Long.
Booked: Harper, Murty.
Goals: Convey 23.
Wolverhampton: Postma, Edwards (Ross 45), Naylor, Lescott, Gyepes, Davies, Ince, Ricketts, Miller (Cort 84), Aliadiere, Frankowski. Subs Not Used: Oakes, Seol, Jones.
Booked: Ricketts, Miller.
Goals: Miller 64.
Ref: P Walton (Northamptonshire).