Youngs, 25, is a converted centre and his Premiership experience is limited to just 12 appearances off the bench for Leicester, nine of which came this season.
But with Rob Webber and Chris Brooker injured, Youngs has been selected alongside his scrum-half brother Ben as one of four hookers in England's touring party.
England head coach Stuart Lancaster will announce his full squad for the three-Test tour tomorrow and Youngs is among a host of uncapped players to have been included,
Lancaster has also recalled Danny Care after the Harlequins scrum-half was excluded from the RBS 6 Nations on disciplinary grounds, along with James Haskell, who was unavailable for the championship as he was playing in Japan.
Bath flanker Carl Fearns will provide back-row options following tour-ending injuries to Tom Croft and Tom Wood, while there are doubts over the fitness of Ben Morgan.
The Wasps pair of wing Christian Wade and lock Joe Launchbury, two of the Aviva Premiership's brightest prospects, have been rewarded for outstanding seasons in a struggling side.
They will be joined in the squad by the uncapped Harlequins quartet of centre George Lowe, lock George Robson, hooker Joe Gray and prop Joe Marler.
Lancaster has also brought some experienced internationals back into the England fold, most notably the Harlequins pair of Care and Ugo Monye.
Care was excluded from England's Six Nations squad on disciplinary grounds following his arrest, and subsequent conviction, for drink driving, but he has been given a second chance by Lancaster.
"I'm on my last chance now and I have a lot to prove to lots of people," Care said.
"I still owe Harlequins an awful lot and I owe Stuart a lot. To have the opportunity to play for England taken away was a very hard lesson to learn, but I will not be making the mistake again."
Monye has not played a Test for England since the 2010 Six Nations, when he lost his place on the wing to Chris Ashton and then saw David Strettle and Charlie Sharples overtake him.
Sharples will miss the tour due to a shoulder injury while Croft has undergone a neck operation. Wood is still plagued by the foot injury that forced him to miss the Six Nations.
Youngs made his only Premiership starts as a hard-hitting centre before being converted to hooker by the current South Africa coach Heyneke Meyer during his brief time in charge at Leicester.
After two years learning his new craft at Nottingham, Youngs returned to Leicester where he has been George Chuter's regular understudy this season.
Youngs and Gray join Dylan Hartley, who has been selected despite not having played since the Six Nations after being banned for biting, and Lee Mears as the hooking options.
Fearns was always going to South Africa this summer, having agreed to join the Stormers Super Rugby side on loan if he did not have any England commitments.
The call came from England forwards coach Graham Rowntree today while he was playing golf.
England play the Barbarians at Twickenham on May 30, the day after the Premiership final, before embarking on their first ever three-Test series in South Africa.
The midweek fixtures will be against teams comprised of South Africa's best Currie Cup players.