The heavy-hitting Northampton lock missed the Six Nations with a knee injury and sat out last weekend's 23-19 victory over Wales with a neck problem.
After seven weeks in camp, Lawes is chomping at the bit for a return to action.
The 22-year-old will start in an England side featuring 13 changes for the trip to Cardiff.
And every one of his team-mates will be relieved that, for the first time since their World Cup preparations began, Lawes will have a Welshman and not one of them in his sights.
"Someone said the other day that when he's playing you can hear it - when he hits players there's a distinctive noise," said England manager Martin Johnson with a certain glee.
"He's got a level of aggression about him and intensity."
Lawes, who made his full Test debut in England's 21-20 victory over Australia in Sydney last summer, prides himself on his aggression.
The 22-year-old admitted he and Manu Tuilagi, England's new powerhouse centre, have been competing to see who can make the biggest tackle in training.
"You are supposed to train how you play and that is what I try and do," said Lawes.
"The other boys aren't that happy but they get over it.
"In training there have been a couple of times when Manu has put in a big hit and I have done one straight afterwards. There is a bit of competition there."
A fortnight ago, Lawes was taken to hospital in an ambulance with his neck in a brace after a collision with Louis Deacon which left him requiring oxygen.
Lawes was cleared of any serious damage but it was a scare for England. Johnson's delight at Lawes' return indicates just how important a figure he will be at the World Cup.
"He's probably the most athletic second row I've seen in terms of pace round the field," said Johnson.
"He gives you some real line-speed, he can hit very hard and he carries the ball very well. He's a pretty instinctive rugby player as well.
"His tight game, his mauling game...his club have asked him to do that a lot and he does it very well. He's a reasonably young man and is developing into an all-round second row."
Sale wing Mark Cueto and London Irish prop Alex Corbisiero are the only two players retained in the starting XV from last weekend's victory over Wales.
Chris Ashton rolled an ankle in training but is expected to be fine to link up with Cueto and Ben Foden in the back three while captain Mike Tindall will resume his midfield partnership with Shontayne Hape.
Toby Flood reclaims the fly-half jersey from Jonny Wilkinson and Richard Wigglesworth's selection at scrum-half is the only change to England's first-choice back division from the Six Nations.
England's centre pairing are perceived to lack the pace or invention required to make a mark at the World Cup - but Johnson was quick to defend Hape's contribution.
"I think Shontayne brings a heck of a lot, but a lot of people don't understand it," he said.
"For a lot of last season he was probably our best defender, he gets you over the gainline and he's a very smart player.
"He doesn't do the one or two eye-catching things that people remember, he does 80 minutes of good solid work.
"When you speak to opposition coaches, a lot of them rate him very, very highly so I will sit here and defend him all day."
In the pack, Hendre Fourie will make his second Test start at openside flanker. Tom Wood and Nick Easter complete the back row and Lawes will pack down with Louis Deacon.
Corbisiero limped off last Saturday with a calf problem but he is fit to start alongside tighthead Dan Cole and hooker Steve Thompson.
As a result of today's selection, wing Ugo Monye, props Paul Doran-Jones and Tim Payne, scrum-half Joe Simpson and loose-forward Chris Robshaw will have played no part in either Wales fixture. Their World Cup aspirations look to be over.
Monye, Doran-Jones and Payne have all been released to play a pre-season match for their clubs this weekend but Johnson will not formally cut his squad from 40 to the final World Cup 30 until August 22.
Andrew Sheridan and Ben Youngs have not appeared either but both are returning from summer surgery and remain central figures in England's World Cup plans.
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