The New Zealand star missed the semi-final against the Scarlets because of a hamstring strain but will take the field for the all-Ireland showdown.
Afoa’s return is Ulster’s only change from the 10 May Scarlets match.
Brian O’Driscoll returns for Leinster, having missed the Amlin Challenge Cup final because of a back injury, but flanker Sean O’Brien has not made it.
British and Irish Lions player O’Brien has been recovering from a knee problem.
Afoa joins this summer’s Ireland captain, Rory Best, and Tom Court in Ulster’s front row, while captain Muller continues his partnership with Dan Tuohy in the second row.
“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 be at our best to beat them.”
Leinster winger Fergus McFadden has made the Leinster line-up after being carried off on a stretcher in last weekend’s Amlin final against Stade Francais because of a neck injury.
Hooker Richard Strauss picked up a shoulder injury in that game but has also recovered in time for the RDS match, and openside flanker Kevin McLaughlin is back after missing the Challenge Cup final because of injury.
Isa Nacewa and Jonathan Sexton will play their final games for Leinster ahead of their summer departures.
Sexton, who passed the 1,000-point milestone for Leinster in the Stade Francais game, is heading to French club Racing Metro, while Nacewa is retiring from the game to return home to New Zealand.
Ulster: J Payne, A Trimble, D Cave, S Olding, T Bowe, P Jackson, R Pienaar; T Court, R Best, J Afoa, J Muller (cpt), D Tuohy, R Diack, C Henry, N Williams.
Replacements: R Herring, C Black, D Fitzpatrick, I Henderson, M McComish, P Marshall, M Allen, P Nelson.
Leinster: R Kearney, F McFadden, B O’Driscoll, I Madigan, I Nacewa, J Sexton, I Boss; C Healy, R Strauss, M Ross, L Cullen (cpt), D Toner,K McLaughlin, S Jennings, J Heaslip.
Replacements: S Cronin, J McGrath, J Hagan, Q Roux, R Ruddock, J Cooney, A Goodman, A Conway
Rugby Friday’s Results
Date Tournament Match
May 25, 2013 Super Rugby Force 19 – 18 Highlanders
Super Rugby Blues 13 – 20 Brumbies