With Rob Kearney and Gordon D'Arcy both sidelined, Madigan reverts to the full-back position with Jonathan Sexton and Eoin Reddan restored as the province's starting half-backs.
McFadden also switches position, moving to inside centre to partner the returning Brian O'Driscoll. The wing spots are filled by Andrew Conway and Isa Nacewa.
Jamie Heaslip will lead team on his 150th career appearance for the province, flanked by two fellow Ireland internationals, Jennings and Kevin McLaughlin, in the back row.
Devin Toner and Damian Browne will combine in the second row, while prop van der Merwe will be joined by Richardt Strauss and Mike Ross in the first line of Leinster's scrum. Cian Healy is unavailable due to a bicep strain.
Ticket sales for Saturday's game are fast approaching the 45,000 mark. Tickets are still on sale online here, and are available to buy from the Leinster Rugby Store (Donnybrook) and Spar (Donnybrook) as well as Ticketmaster outlets nationwide.
There will be tickets on sale from 2.30pm on Saturday from the Clyde Court Hotel (formerly the Berkeley Court) near the ground.
LEINSTER (v Munster): Ian Madigan; Andrew Conway, Brian O'Driscoll, Fergus McFadden, Isa Nacewa; Jonathan Sexton, Eoin Reddan; Heinke van der Merwe, Richardt Strauss, Mike Ross, Damian Browne, Devin Toner, Kevin McLaughlin, Shane Jennings, Jamie Heaslip (capt).
Replacements: Sean Cronin, Jack McGrath, Jamie Hagan, Tom Denton, Jordi Murphy, John Cooney, Noel Reid, Fionn Carr.