The Norwich City winger caused havoc from the first minute as Gareth Southgate's charges ran out comfortable winners on a damp Monday night at the Liberty Stadium
The Norwich City winger, who scored the winner in a 1-0 winner over Geraint Williams's side earlier in the campaign, capped a fine performance with two pin-point finishes before the break.
Gwion Edwards had briefly pulled the home side level but, after hitting the post, Redmond sealed his treble with a curled strike in stoppage time.
Gareth Southgate opted to hand Everton's Luke Garbutt a debut at left-back in the absence of Luke Shaw and Jon Flanagan while Danny Ings was preferred to Tottenham's Harry Kane in the lone striker's role.
Garbutt was involved straight away, with he and Redmond causing right-back Kieran Freeman no end of problems on the England left, and the latter almost created an opener as his chipped cross was headed over the top by Jesse Lingard from six yards.
Former Birmingham City winger Redmond was the best player on the pitch in the opening stages, and he eventually gave England an early lead as he robbed Lloyd Isgrove, cut inside and fired an effort into the bottom corner at Connor Roberts's near post.
That strike sprung the hosts into life, and Wes Burns tested Jack Butland for the first time as he hit an angled drive that the goalkeeper was forced to tip behind.
From the resulting corner, though, they were level as Edwards lost his marker in the six-yard box and powered a header past England captain Butland.
The Stoke goalkeeper was called into action soon after as he stood tall to push Isgrove's attempted chip finish away after a fine through-ball from Burns.
England were certainly rocked, but after Redmond and Tom Ince swapped wings the visitors' impact grew once more.
Roberts had to be at his best to deny both Ings and Lingard twice within a matter of seconds before a long-range Garbutt drive was pushed away by the released Cheltenham Town goalkeeper.
England's second came with seven minutes of the first half remaining as Garbutt and Lingard combined to find Redmond in space on the right, and his deflected drive arrowed into the bottom corner.
Southgate's young charges continued to keep the ball effectively early in the second period, but other than a fine run and strike against the post from Redmond, England struggled to breakdown the Welsh defence.
Lingard and substitute Saido Berahino almost added a third late on as the home side looked devoid of ideas before Redmond put the icing on the cake in the 92nd minute as he broke from the halfway line before curling an effort past a hapless Roberts.