The All Black prop will Ireland's summer tour captain, Rory Best, and Tom Court in the front row, while Ulster's regular captain Johann Muller continues his partnership with Dan Tuohy in the second row.
Robbie Diack and Chris Henry start either side of the scrum with the RaboDirect PRO12 Players' Player of the Year, Nick Williams, selected at number 8.
Ruan Pienaar starts at scrum half, with Paddy Jackson named at out-half. The 20-year-old Stuart Olding partners Darren Cave in midfield with Lions winger Tommy Bowe joining Andrew Trimble and Jared Payne in the back-three.
Commenting on his selection, Ulster head coach Mark Anscombe said: "It's great to be able to welcome John back into the starting line-up. John and players like Ruan (Pienaar) and Johann (Muller) have been part of World Cup winning squads.
"When the big moments come, they are cool heads under pressure and you can't put a price on that. When you put them together with our Ireland internationals and our excellent young players like Stuart Olding then you have a great mix.
"However, Leinster are a quality team and we have a huge amount of respect for them. They will ask a lot of questions of us and we will have to play at our very best to beat them.
"This is a massive match, a local derby and it is an occasion that everyone at Ulster is looking forward to. In recent seasons Ulster have been the bridesmaids too often. We have done our learning - it's now time to step up and to prove that we are good enough."
ULSTER (v Leinster): Jared Payne; Andrew Trimble, Darren Cave, Stuart Olding, Tommy Bowe; Paddy Jackson, Ruan Pienaar; Tom Court, Rory Best, John Afoa, Johann Muller (capt), Dan Tuohy, Robbie Diack, Chris Henry, Nick Williams.
Replacements: Rob Herring, Callum Black, Declan Fitzpatrick, Iain Henderson, Mike McComish, Paul Marshall, Michael Allen, Peter Nelson.