A thoroughly dominant display from the Saddlers saw Miller wreak havoc on a sorry Stags defence, netting either side of Ash Taylor's towering header.
And while the visitors struck towards the end through Danny Johnson, Matt Taylor has plenty to smile about with his charges now three games unbeaten in League Two.
Miller kicked things off in style as he found the net in a matter of minutes.
Taylor then made the most of Mansfield's frailty from set plays before centre forward Miller got a lovely second.
Johnson's strike denied Walsall a clean sheet, but the end result was not in doubt at any point. Make no mistake, they were the better side.
The Saddlers have been craving a striker and in Miller, they may well have their man. He had an outstanding afternoon.
Three goals and three points, things are looking pretty good.
Walsall made two changes to the starting line-up – both of them enforced.
Centre-half Rollin Menayese could not play against his parent club while skipper Joss Labadie started his three-match league ban after being shown a straight red card at Bradford.
Taylor and Tyrese Shade were those to come in, in an attack-minded team.
Boss Taylor had called for the Saddlers to be 'aggressive' and take the game to Mansfield. They got off to a perfect start as well.
Walsall were ahead after just five minutes as Miller displayed both tenacity and talent, grabbing his first goal since joining from Barnsley on deadline day.
Latching onto Kieran Phillips' over-the-top ball, the Tykes loanee outfought Stags centre-half Elliott Hewitt before firing the ball low into the far corner.
It was an excellently-taken goal and had an uncanny resemblance to Conor Wilkinson's winner against Stevenage a couple of weeks ago.
The visiting Mansfield fans continued to voice their support despite falling behind, trying to will their team on.
They had captain Oli Hawkins force a couple of saves from Carl Rushworth, too – one a routine catch and the other needing to be acrobatically tipped over.
But Walsall were looking dangerous.
Miller, buoyed by his goal, found space again and unleashed a sensational half-volley from 25 yards which rattled the crossbar.
Shade's follow-up was then fumbled by Nathan Bishop, with the onrushing Brendan Kiernan just unable to reach the loose ball.
The Saddlers had the bit between their teeth and, unsurprisingly, they soon doubled their lead.
Mansfield's failure to deal with set pieces properly has been a big problem over the past several weeks, and Taylor was the latest to take advantage with a bullet header.
Jack Earing's inswinging corner was met emphatically by the defender. Meat and drink for him.
The Stags had come into the game with the joint-worst defensive record in the division, and it was quickly becoming apparent as to why.
Nigel Clough's lot consistently failed to deal with routine balls upfield.
Hayden White clipped one past the backline and Kiernan nearly made it three, only to be denied by Bishop's sharp stop.
Walsall were certainly worth their lead going into the break, although Mansfield's woeful defending had given them a helping hand.
The interesting decision to have Kiernan in the No.10 position rather than wide left had worked a treat.
Liam Kinsella was everywhere while Miller led the line with aplomb. And it soon got better.
Mansfield had tried to stem the tide by bringing on Johnson and Farrend Rawson for the start of the second half, but the determined Miller could not be stopped.
He brushed Richard Nartey off the ball this time before coolly slotting it beyond Bishop.
In that one-on-one situation, he never looked like he was going to miss. Ice in his veins.
The comfort of that third goal brought on a carnival atmosphere at the Banks's, and Manny Monthe was not far away from giving the fans a unique fourth to cheer.
His clearance from the halfway line would have gone in had it not been for Bishop anxiously scrambling back and making the save.
Telling the story, the Stags had made all three changes by the hour. The Saddlers, meanwhile, were quite happy to keep things as they were.
A switch eventually came in the 71st minute as Emmanuel Osadebe replaced Shade.
Walsall continued to push as Miller saw a near-post effort stopped, while the Mansfield supporters chanted 'if we score, we're on the pitch'.
The Stags did grab a late consolation as Johnson lashed home from close range – one or two indeed making their way onto the turf.
Ultimately, though, the Saddlers were convincing winners. Back-to-back home victories and momentum is on their side.
Their best display under Taylor.
Walsall (4-2-3-1): Rushworth; White, Taylor, Monthe, Ward (c); Kinsella, Earing; Phillips (Perry, 90), Kiernan, Shade (Osadebe, 71); Miller
Subs not used: Rose (gk), Leak, Mills, Willis, Bates
Goals: Miller (5, 48), Taylor (22)
Mansfield (4-3-3): Bishop; Gordon, Hewitt (Rawson, 46), Nartey, McLaughlin; Maris (Bowery, 62), Stirk, Lapslie; Oates (Johnson, 46), Hawkins (c), Sinclair
Subs not used: Shelvey (gk), Charsley, Burke, Law
Goal: Johnson (84)
Attendance: 5,203 (1,008 Mansfield fans)
Referee: David Rock