Tigers fly-half George Ford converted two of the six tries and added four penalties, while club colleague Matt Everard also started the game.
Tries from Charlie Matthews, Ryan Mills, Matt Kvesic, Andy Short, Mike Haywood and captain Alex Gray secured the win and a first Grand Slam since 2008.
Tigers prop Ryan Bower is also in the england Under-20s squad this season, making his dedbut in the away win over Wales in February before illness.
Ford said: "One of our season objectives was to win the Grand Slam, and that’s what we’ve done. It’s not us being arrogant, it’s being confident and pushing ourselves to be the best we can.
"We’re absolutely delighted. To secure the win out in Ireland took some doing but we kept the scoreboard kicking over nicely and here we are, we’ve done it.
"That first win over in Wales was crucial, it set us up on a strong platform and then the wins against Italy, France and Scotland moved us towards creating the Grand Slam opportunity.
"Ireland were pretty physical at times and they caused us a few problems. We missed a couple of opportunities to score early on but I knew if we kept playing in the same way we’d create more.
"We can be harsh on ourselves and say that we need to be nailing all these chances, but there are a few months until the Junior World Championship starts in Italy and I’m sure we’ll work on our game even further."
England U20: 15 Ben Ransom, 14 Andy Short, 13 Elliot Daly, 12 Ryan Mills, 11 Jonathan Joseph, 10 George Ford, 9 Chris Cook; 1 Mako Vunipola, 2 Mike Haywood, 3 Henry Thomas, 4 Joe Launchbury, 5 Charlie Matthews, 6 Matt Kvesic, 7 Matt Everard, 8 Alex Gray
Replacements: 16 Rob Buchanan for Haywood 52 mins, 17 Will Collier for Vunipola 65 mins, 18 Addison Lockley for Joe Launchbury 75 mins, 19 Sam Jones for Everard 62 mins, 20 Dan Robson for Cook 60 mins, 21 Owen Farrell for Ryan Mills 45 mins, 22 Jamie Elliott for Jonathan Joseph 30 mins
