Keogh, 24, will make his first start since Decemer 27, as Gaffney swaps both himself and Jim Williams for the benched Alan Quinlan and hamstring victim Denis Leamy.
Also in the forwards, Tom Bowman comes in for Irish international Donncha O'Callaghan - a starter in tomorrow's IRB Tsunami Rugby Aid match - for his eleventh appearance of the league campaign.
The three other changes from Munster's 25-19 defeat of Glasgow last time out, see Rob Henderson and Shaun Payne recalled in midfield, and Mike Prendergast getting the nod for the scrum-half berth over Old Crescent's Eoin Reddan.
Celtic League: Week 17: Saturday, March 5 (live Setanta Sports)Cardiff Blues v Munster, Arms Park, 5.30pm
Head-to-head since 2003: Cardiff 1, Munster 2League form: Cardiff LLLWL, Munster WWWLWTop scorers: Cardiff: Lee Thomas 72 points / Dean Dewdney 4 tries; Munster: Paul Burke 92 / Christian Cullen 8
Cardiff: Nick Macleod; Dean Dewdney, Tristan Davies, Lee Thomas, Craig Morgan; Nick Robinson, Ryan Powell; Martin Jones, Gareth Williams, Ben Evans, Craig Quinnell (Capt), Deiniol Jones, Maama Molitika, Robin Sowden-Taylor, Kort Schubert.Replacements: Jonny Vaughton, Dafydd Hewitt, Richard Smith, Nathan Llewellyn, Rhys Thomas, James Goode, Nathan Thomas.
(15) Christian Cullen(14) John Kelly(13) Shaun Payne(12) Rob Henderson(11) Anthony Horgan(10) Paul Burke(9) Mike Prendergast(1) Marcus Horan(2) Frankie Sheahan(3) Gordon McIlwham(4) Tom Bowman(5) Trevor Hogan
(16) Frankie Roche(17) Jerry Flannery(18) Tom Hayes(19) Alan Quinlan(20) Eoin Reddan(21) Jason Holland(22) Paul Devlin
Referee: Mike Hall (Scotland)
Sunday, March 6:Leinster v Neath-Swansea Ospreys, Donnybrook, 4.45pm (live Setanta Sports)
Head-to-head since 2003: Leinster 2, Ospreys 1, Draw 1League form: Leinster WLLWL, Ospreys WWWDWTop scorers: Leinster: David Holwell 86 points / Denis Hickie 5 tries; Ospreys: Gavin Henson 139 /David Bishop 4
Backs: Brian O'Riordan, Guy Easterby, Brian O'Meara, David Holwell, David McAllister, Gordon D'Arcy, Christian Warner, Kieran Lewis, James Norton, John McWeeney, Gary Brown, David Hewitt.
Forwards: John Lyne, Emmett Byrne, Ricky Nebbett, David Blaney, Gavin Hickie, Ben Gissing, Ciaran Potts, Aidan McCullen, Des Dillon, Niall Ronan, Shane Jennings, Victor Costello, Eric Miller, Keith Gleeson.
Backs: Adrian Durston, Stefan Terblanche, Richard Mustoe, Dave Tiueti, Elvis Seveali'i, Andrew Bishop, Matthew Jones, Sean Connor, Jason Spice, Richard Rees.
Forwards: Andrew Millward, Duncan Jones, Cai Griffiths, Richard Hibbard, Barry Williams (Capt), Andrew Newman, Lyndon Bateman, Alun Wyn Jones, Richard Pugh, James Bater, Jonathan Thomas, Steve Tandy, Nathan Bonner-Evans.
Referee: Andy Ireland (Scotland)