The Cardiff Blues back-row forward is one of five uncapped players in the 35-man group named by interim coach Rob Howley on Tuesday morning, joining Blues back-row colleague Josh Navidi, Ospreys wing Eli Walker and lock James King, plus Newport Gwent Dragons second-row forward Andrew Coombs.
Born in Nelspruit, Pretorius qualifies on residency for Wales and became available for selection last month.
His availability is a boost for Howley, who is without second-rowers Alun-Wyn Jones, Luke Charteris and Bradley Davies while fly-half Rhys Priestland and prop Aaron Jarvis are also injury
absentees ahead of the opening game of their Six Nations title defence against Ireland on 2 February.
Clermont Auvergne full-back Lee Byrne, who has not featured in a Wales matchday 23 since the 2011 World Cup, has been recalled alongside Exeter prop Craig Mitchell.
Prop Adam Jones also returns after missing the autumn internationals with injury, but former skipper Ryan Jones is unlikely to be ready to face Ireland because of a dislocated thumb.
Howley said: "We have put together a very experienced squad and complimented that by rewarding the in-form players with a call-up.
"The players in the squad have been playing really well, and we have been pleased with their individual performances.
"We have a group of players who know how to win big matches and have experienced success. We are adding to that players who have stood out and performed well for the regions this season."
Wales Squad:
Backs: L Byrne (Clermont Auvergne), L Williams (Scarlets), L Halfpenny (Cardiff Blues), E Walker (Ospreys), G North (Scarlets), A Cuthbert (Cardiff Blues), S Williams (Scarlets), J Roberts (Cardiff Blues), J Davies (Scarlets), J Hook (Perpignan), D Biggar (Ospreys), M Phillips (Bayonne), T Knoyle (Scarlets), Lloyd Williams (Cardiff Blues)
Forwards: S Andrews (Cardiff Blues), C Mitchell (Exeter), A Jones (Ospreys) P James (Bath), G Jenkins (Toulon), R Bevington (Ospreys), R Hibbard (Ospreys), K Owens (Scarlets), M Rees (Scarlets), R Jones (Ospreys) L Reed (Blues), I Evans (Ospreys), J King (Ospreys), A Coombs (Newport Gwent Dragons), J Turnbull (Scarlets), J Navidi (Cardiff Blues), A Shingler (Scarlets), J Tipuric (Ospreys), S Warburton (Cardiff Blues, capt) T Faletau (Newport Gwent Dragons), A Pretorius (Cardiff Blues)
Source : http://www1.skysports.com/rugby-union/news/12507/8398019/Andries-Pretorius-included-in-Wales-squad-for-Six-Nations-Championship
