Youngs, who is the older brother of scrum-half Ben, made his Leicester debut as a centre before being told to switch to the front row in the 2009/10 season.
The former England U20s star spent two years learning his trade at Championship side Nottingham and his international call up comes after just one season back in the Tigers first-team squad.
Youngs has had to play third fiddle to George Chuter and Rob Hawkins at Welford Road this term but England head coach Stuart Lancaster clearly believes the 25-year-old can make a big impact in the run up to the 2015 World Cup.
Lancaster has also turned to a number of other new faces, with four of the England U20s side that reached last year's World Cup Final included. Wasps duo Christian Wade and Joe Launchbury and London Irish centre Jonathan Joseph join Saracens playmaker Owen Farrell in the squad.
Newly-named Aviva Premiership player of the year Chris Robshaw retains the captaincy while there are recalls for Otago Highlanders back rower James Haskell, 2009 Lion Ugo Monye and Harlequins scrum-half Danny Care who missed the World Cup through injury and the RBS 6 Nations through suspension after being charged with drink driving.
There are 13 uncapped players in total, with Bath flanker Carl Fearns, Quins hooker Joe Gray and Leicester lock Graham Kitchener among them.
There is no place for new Sale fly-half Danny Cipriani despite his early release from the Melbourne Rebels, while Tom Croft, Courtney Lawes, Louis Deacon, Tom Wood, Rob Webber, Charlie Sharples, Joe Simpson, Chris Brooker, Stuart Hooper, Nick Wood and David Wilson are all out injured and Claum Clark is suspended.
"There is a real excitement about this squad," said Lancaster.
"We have a massive challenge ahead of us but it is one that everybody involved - players, coaches and management - is looking forward to.
"While certain players are not available because of inevitable injuries at this time of the season, we have been able to select the bulk of the squad from the RBS 6 Nations and the Saxons, while also taking with us four of the U20 team which reached last June's Junior World Championship final and we see the return of two experienced internationals in Danny Care and James Haskell."
England squad to tour South Africa
Forwards (23): Mouritz Botha (Saracens), Dan Cole (Leicester Tigers), Alex Corbisiero (London Irish), Paul Doran Jones (Northampton Saints), Phil Dowson (Northampton Saints), Carl Fearns (Bath Rugby), Joe Gray (Harlequins), Dylan Hartley (Northampton Saints), James Haskell (Otago Highlanders), Tom Johnson (Exeter Chiefs), Graham Kitchener (Leicester Tigers), Joe Launchbury (London Wasps), Joe Marler (Harlequins), Lee Mears (Bath Rugby), Ben Morgan (Scarlets), Matt Mullan (Worcester Warriors), Tom Palmer (Stade Francais), Geoff Parling (Leicester Tigers), Chris Robshaw (capt, Harlequins), George Robson (Harlequins), Matt Stevens (Saracens), Thomas Waldrom (Leicester Tigers), Tom Youngs (Leicester Tigers)
Backs (19): Anthony Allen (Leicester Tigers), Chris Ashton (Northampton Saints), Brad Barritt (Saracens), Mike Brown (Harlequins), Danny Care (Harlequins) Lee Dickson (Northampton Saints), Owen Farrell (Saracens), Toby Flood (Leicester Tigers), Ben Foden (Northampton Saints), Alex Goode (Saracens), Charlie Hodgson (Saracens), Jonathan Joseph (London Irish), George Lowe (Harlequins), Ugo Monye (Harlequins), David Strettle (Saracens), Manu Tuilagi (Leicester Tigers), Jordan Turner-Hall (Harlequins), Christian Wade (London Wasps), Ben Youngs (Leicester Tigers)
NB Bold denotes Lion
England's fixtures in South Africa
Saturday, June 9: South Africa v England (King's Park, Durban, 4pm BST)
Wednesday, June 13: SA Barbarians South v England (GWK Park, Kimberley, 1.30pm BST)
Saturday, June 16: South Africa v England (Coca-Cola Park, Johannesburg, 4pm BST)
Tuesday, June 19: SA Barbarians North v England (Profert Olen Park, Potchefstroom, 6.10pm BST)
Saturday, June 23: South Africa v England (Nelson Mandela Bay Stadium, Port Elizabeth 4pm BST)