Racing Metro's Francois Steyn has also been named in the Springboks' 30-man panel, but he will not be available for the Aviva Stadium clash next Saturday.
Pienaar's Ulster team-mate BJ Botha is ruled out of contention due to a wrist injury, but ex-Leinster prop CJ van der Linde will be involved.
Peter de Villiers' selection includes six uncapped players, headed by South Africa Under-20 starlets Elton Jantjies and Patrick Lambie.
The other newcomers to Test rugby are Cheetahs prop Coenie Oosthuizen and the Sharks trio of winger Lwazi Mvovo and back rowers Willem Alberts and Keegan Daniel.
"We've rewarded players for their form in what was a difficult selection as there were a number of others who were part of our preliminary squad who were very close to selection," admitted de Villiers.
"But we looked at the players who were performing now in our selection criteria as we need to be on top form from the first kick-off in Ireland.
"It's a new-look squad but it has a good backbone of experience for what is going to be a challenging tour."
The Springboks, led by tour captain Victor Matfield, will take on Ireland (November 6), Wales (November 13), Scotland (November 20), England (November 27) and the Barbarians (December 4) in the coming weeks. The players and management assembled over the weekend in Johannesburg.
As well as Botha, the reigning World Champions have regular skipper John Smit, Jaque Fourie, Wynand Olivier, Andries Bekker, Fourie du Preez, Heinrich Brüssow, JP Pietersen, Gurthrö Steenkamp and Butch James on their injury list.
Scrum half Ricky Januarie was a late withdrawal from the 'Boks tour squad, due to the knee injury he picked up during last Saturday's Currie Cup final in Durban.
With former Munster centre Jean de Villiers troubled by a groin problem and his Western Province team-mate Juan de Jongh nursing an ankle injury, Sharks centre Adi Jacobs has been drafted into the squad as precautionary cover.
The Springboks boss added: "We will monitor Juan and Jean's progress in the next couple of days.
"We have had a number of injuries among our senior centres so we decided it was essential to have some experienced cover on hand and in the group just in case."
SOUTH AFRICA Squad - Backs (13): Gio Aplon (Western Province), Bjorn Basson (Blue Bulls), Juan de Jongh (Western Province), Jean de Villiers (Western Province), Francois Hougaard (Blue Bulls), Bryan Habana (Western Province), Adi Jacobs (Sharks), Elton Jantjies (Golden Lions), Patrick Lambie (Sharks), Lwazi Mvovo (Sharks), Ruan Pienaar (Ulster), Francois Steyn (Racing Metro), Morne Steyn (Blue Bulls).
Forwards (17): Willem Alberts (Sharks), Bakkies Botha (Blue Bulls), Schalk Burger (Western Province), Keegan Daniel (Sharks), Bismarck du Plessis (Sharks), Jannie du Plessis (Sharks), Alistair Hargreaves (Sharks), Ryan Kankowski (Sharks), Victor Matfield (Blue Bulls) (capt), Tendai Mtawarira (Sharks), Coenie Oosthuizen (Cheetahs), Chiliboy Ralepelle (Blue Bulls), Juan Smith (Cheetahs), Pierre Spies (Blue Bulls), Adriaan Strauss (Cheetahs), CJ van der Linde (Cheetahs), Flip van der Merwe (Blue Bulls).