The squad of 23 players, comprising of Test stars from New Zealand, France, Australia, Ireland, Samoa, Tonga, Georgia and South Africa, boasts a total of 707 caps between them.
“The group of players who have been selected for this match are not only very experienced, but are all in very good form at the moment,” said Mallett.
The latest additions to the squad of 23 include four All Blacks with 185 Tests worth of experience between them.
Experienced hooker Andrew Hore, who has 83 caps for New Zealand, heads the list of Kiwis, followed by scrumhalf Jimmy Cowan (51 Tests) and speedsters Sitiveni Sivivatu (45 caps) and Rene Ranger (6 caps).
French Test players Aurelien Rougerie ( 71 caps) and Alexandre Lapandry ( 6 caps) are included, as well as loose forwards Roger Wilson from Ireland (1 cap) and Mamuka Gorgodze from Georgia (51 caps).
Samoan lock Joe Tekori (26 caps) and Tongan prop Sona Taumalolo (5 caps) will add a Pacific flavour to the team.
The only uncapped members of the squad are Rory Kockott and Schalk Ferreira.
The most experienced of the South African contingent in the squad is BJ Botha, who has 25 Springbok caps to his name, followed by Juandré Kruger (17 caps), Schalk Brits (5 caps) and Alistair Hargreaves (4 caps).
“I’m very happy that the final pieces of the jigsaw are now falling into place,” added Mallett.
“Despite the very short preparation time, I’m really looking forward to getting together with this group of very talented players and preparing them for this match.
“It promises to be a very exciting match, looking at the talent assembled in this strong squad.
“I’m sure they are all relishing the opportunity to play against the Springboks in South Africa.
“It’s also a rare chance to see a World XV-style team playing in South Africa, and where better than the oldest Test venue in the country?”
Unfortunately French loose forward Julien Bonnaire, who has 75 Test caps to his name, was forced to withdraw from the squad because of an injury.
World XV squad: James O’Connor, Drew Mitchell, Hosea Gear, Sititiveni Sivivatu, Aurelien Rougerie, Rene Ranger, Matt Giteau, François Trinh-Duc, Rory Kockott, Jimmy Cowan, Steffon Armitage, Alexandre Lapandry, Roger Wilson, Mamuka Gorgodze, Alistair Hargreaves, Joe Tekori, Juandré Kruger, Schalk Brits, Andrew Hore, Schalk Ferreira, Sona Taumololo, BJ Botha Carl Hayman.