The 22-year-old Cardiff Blues flanker fills a vacancy created by hooker Matthew Rees' neck injury, with his promotion being confirmed on Monday by Wales coach Warren Gatland.
Gatland's 30-man World Cup squad, announced at the Millennium Stadium, contains one uncapped player - Scarlets hooker Ken Owens - who received an 11th-hour call to replace ankle injury victim Richard Hibbard.
Hibbard was hurt during Saturday's World Cup warm-up victory over Argentina in his comeback match after undergoing summer shoulder surgery. Owens joins fellow squad hookers Huw Bennett and Lloyd Burns.
As expected, there are few surprises in the squad, although 99 times-capped Cardiff Blues flanker Martyn Williams misses out on playing in his fourth World Cup.
Gatland has opted for a split of 16 forwards and 14 backs, with Sale Sharks' Andy Powell gaining one of the back-row slots, while scrum-half prospects Tavis Knoyle and Lloyd Williams also gain opportunities.
Scarlets wing George North, at 19, is the youngest player chosen, with Gatland also selecting two 20-year-olds in Scarlets centre Scott Williams and Newport Gwent Dragons number eight Toby Faletau.
Rees, Hibbard, centre Gavin Henson (wrist) and wing Morgan Stoddart (broken leg) were all unavailable for selection, but prop Gethin Jenkins makes the cut despite ongoing concerns about a calf muscle problem.
Players overlooked by Gatland include include Williams, scrum-half Dwayne Peel, who captained Wales in their first game of the 2007 World Cup, plus back-row forwards Josh Turnbull, Jonathan Thomas, Gareth Delve and Justin Tipuric.
Wales kick off their World Cup campaign against South Africa in Wellington on September 11, followed by other pool stage appointments with Samoa, Namibia and Fiji.
Wales squad for the Rugby World Cup:
Full-backs: Lee Byrne (Clermont Auvergne), Rhys Priestland (Scarlets).
Wings: George North (Scarlets), Shane Williams (Ospreys), Leigh Halfpenny (Cardiff Blues).
Centres: Jonathan Davies (Scarlets), Jamie Roberts (Cardiff Blues), Scott Williams (Scarlets).
Fly-halves: James Hook (Perpignan), Stephen Jones (Scarlets).
Scrum-halves: Mike Phillips (Bayonne), Tavis Knoyle (Scarlets), Lloyd Williams (Cardiff Blues).
Props: Paul James (Ospreys), Gethin Jenkins (Cardiff Blues), Adam Jones (Ospreys), Craig Mitchell (Exeter), Ryan Bevington (Ospreys).
Hookers: Huw Bennett (Ospreys), Lloyd Burns (Newport Gwent Dragons), Ken Owens (Scarlets).
Locks: Bradley Davies (Cardiff Blues), Alun-Wyn Jones (Ospreys), Luke Charteris (Newport Gwent Dragons).
Back-row: Ryan Jones (Ospreys), Dan Lydiate (Newport Gwent Dragons), Josh Turnbull (Scarlets), Sam Warburton (Cardiff Blues, capt), Martyn Williams (Cardiff Blues), Toby Faletau (Newport Gwent Dragons.
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