Handscomb was called up to Australia’s squad as a replacement for Shaun Marsh, who fractured his forearm after being struck in the nets last week.
The right-hander – who was omitted from Australia’s original squad despite featuring in the recent series wins over Pakistan and India – will now slot into the batting line-up for Thursday’s semi-final.
"I'll tell you the truth. Peter Handscomb will definitely play, 100 percent," said Langer. "He deserves it, he was really stiff not to be on this tour. He was so unlucky not to be in the initial squad after what he'd done to help us get to that point.
"He's in good form, he played well for Australia A, he gives us nice balance through that middle order, he's got great temperament, he plays spin well and he's on top of his game. So he'll definitely play."
NEWS: Australia head coach Justin Langer confirms Peter Handscomb will come into Australia's XI in place of Usman Khawaja for the #CWC19 semi-final against England on Thursday.— Cricket World Cup (@cricketworldcup) July 9, 2019
He'll be playing his first World Cup game. No pressure... ?#AUSvENG | #CmonAussie pic.twitter.com/DyZcNA8W4w
Australia have also received a fitness boost with Marcus Stoinis fit to play having recovered from an issue with his side. "He looks good," said Langer after Australia hit the nets at Edgbaston on Tuesday. "It was a very good net session actually, there was a bit of heat again, it was very competitive and that always brings the best out in Stoin. He did a good job today and he's fit to go."
Langer also added that Matthew Wade is set to join Australia’s squad in place of Usman Khawaja, who suffered a hamstring strain in the final group stage match with the Proteas. Wade has been with Australia's squad as cover for the last few days, having been on the Australia A tour of England. The Tasmania batsman has impressed for Australia A with scores of 117, 155, 41 and 42 in his four List A innings on the tour.
"He's played a lot of international cricket before, he's a real seasoned pro, he's had an unbelievable 12 months or so in domestic cricket," said Langer. "With his experience, if he plays, then we're confident he'll do a really good job for us."