Britton and Robson maintain their starting positions of hooker and scrum half respectively while Mills moves to inside centre from fly half.
Adams Park hosts the match, and while a win for Ireland would secure a Grand Slam, an English victory would all but give Rob Hunter's side a second successive Championship win, thanks to their impressive points difference of +118.
Bath Rugby fly half Tom Heathcote comes into the side, England's fifth No. 10 of the competition, while there are first starts for Sale Sharks' Will Addison and London Wasps prop Alec Hepburn.
Head Coach Hunter said:
"We're happy with where we are as a side. We learnt a lot of tough lessons against France last weekend and we'll be looking to bounce back against what is a very organised, good quality Irish side.
"Ireland are going for the Grand Slam but our focus is on ourselves, we've got things that we need to fix up as we build towards the IRB Junior World Championship. Saying that, we know what is at stake for both teams on Friday, but the main motivation is to perform better than we did last week."
On Heathcote's inclusion, Hunter added:
"It's a shame that we haven't had a chance to see Tom at 10 sooner, but by the same token it's fantastic that he's been playing for Bath and doing very well.
"It's great to get him in the shirt, we have had a lot of changes in that position, and on the one hand you would maybe prefer to have a more settled side, but on the other it bodes well to have such strength in depth."
England Under 20 side to play Ireland
15 Anthony Watson (London Irish)
14 Marland Yarde (London Irish)
13 Will Addison (Sale Sharks)
12 Ryan Mills (Gloucester Rugby)
11 Charlie Walker (Harlequins)
10 Tom Heathcote (Bath Rugby)
9 Dan Robson (Gloucester Rugby)
1 Alec Hepburn (London Wasps)
2 Koree Britton (Gloucester Rugby)
3 Kyle Sinckler (Harlequins)
4 Tom Price (Leicester Tigers)
5 Dom Barrow (Leeds Carnegie)
6 Matt Kvesic (Worcester Warriors)
7 Chris Walker (Leeds Carnegie) (C)
8 Jack Clifford (Harlequins)
16 Nathan Morris (London Wasps)
17 Luke Cowan-Dickie (Exeter Chiefs)
18 Ross Harrison (Sale Sharks)
19 George Merrick (Harlequins)
20 David Sisi (London Irish)
21 Ben Spencer (Saracens)
22 Sam Hill (Exeter Chiefs)
23 Ben Ransom (Saracens)
Content courtesy of RFU