Alex Mitchell continued his scoring streak at the World Rugby U20 Championships to help England maintain their unbeaten start.
The scrum-half crossed from close range against Samoa in Round 1, and came off the bench on Sunday to settle England's second half nerves and claim a maximum haul in the process.
England had led 24-10 at half-time thanks to three converted tries and a penalty, but Wales fought back after the break with two tries of their own.
However, Mitchell settled England's nerves, also earning the extra point while Malins sent over a conversion and drop goal before Joe Goodchild's late try for Wales.
England head coach Ian Vass said: “Overall you have to be pleased with a bonus point victory and I thought our boys worked really, really hard and we had some purple patches where we played some really good stuff and we had some periods where we defended really well.
“There probably wasn’t a flow to the game and it wasn’t the best looking game but in these pool stages it’s all about getting through them.”
England's final pool match is a winner-takes-all clash with Australia on Thursday, with the result between these two hitherto unbeaten teams deciding who tops Pool A going into the semi-finals.