Twenty-nine of the squad have been capped at full international level, a further eight have played for the Saxons, while there are four members of last season's Under 20 IRB Junior World Championship squad - Saracens' Owen Farrell (Land Rover Discovery of the Season), London Wasps Christian Wade, the second highest try scorer in the Aviva Premiership (nine), London Irish back Jonathan Joseph and London Wasps lock Joe Launchbury.
Mullan said: "I am naturally really pleased to get the call-up from the senior England set-up and I'm now looking forward to the tour to South Africa.
"My season has gone really well in the Aviva Premiership and I feel I have got better with each game to help the Warriors retain out top-flight status.
"There is obviously very strong competition for places within the squad, but it is my job to go out to South Africa and do all I can to push my claims for more international rugby. It's a big opportunity for me and one I'm looking forward to taking."
Head Coach Richard Hill added: "Everyone at Warriors is delighted for Matt that has been given this fully deserved call-up by England.
"Matt has had an outstanding season for the club and been consistently excellent for us. He has got better and better with a full season under his belt and shown why he is one of the most highly regarded and talented props in the English game with a big future.
"As a club, we were very pleased when Matt committed himself to the club earlier this season by signing a new contract and this call-up shows that our players can gain the international recognition they deserve here at Sixways.