Patchell will feature in league action for the first time since the start of November – when he also faced Munster – as Blues look to claim a crucial victory in Cork and climb the league table.
Director of Rugby Mark Hammett makes a total of eight changes to the team that started the last Guinness PRO12 game against Leinster in mid-January.
Wing Richard Smith is called into the starting line-up while Patchell will join forces with Lloyd Williams in a new-look half back pairing. Cory Allen is back in midfield alongside Gavin Evans after being released by Wales.
Hooker Matthew Rees captains the team from the front row where he packs down alongside the called-up Sam Hobbs and Adam Jones.
A new second row pairing will see Filo Paulo and Macauley Cook, who this week agreed a new long-term deal at the region, combine.
Number Eight Manoa Vosawai is also back in the starting line-up, with Josh Navidi moving to the number seven jersey as the Italian international returns.
Josh Turnbull is named at blindside flanker and will make his 100th appearance in the PRO12.
Centre Tom Isaacs is named among the replacements as Blues look to repeat the 17-6 victory they claimed the last time the two teams met at the Irish Independent Park back in January 2013.
Director of Rugby Mark Hammett said: “We’re looking forward to returning to the Guinness PRO12 as we start a big month of fixtures as we look to move up the table.
“We’ve played really well at times this season without always getting the results. We now need to start getting some victories on the board.
“We welcome back a number of players who have been able to have a break for rest and recovery during the cup window and we look forward to seeing the benefit of that spell when we play in Ireland.”
Cardiff Blues: 15 Joaquin Tuculet, 14 Richard Smith, 13 Cory Allen, 12 Gavin Evans, 11 Lucas Amorosino, 10 Rhys Patchell, 9 Lloyd Williams; 1Sam Hobbs, 2 Matthew Rees (c), 3 Adam Jones, 4 Macauley Cook, 5 Filo Paulo, 6 Josh Turnbull, 7 Josh Navidi, 8 Manoa Vosawai
Replacements: 16 Kristian Dacey, 17 Thomas Davies, 18Taufa’ao Filise, 19 Miles Normandale, 20 Ellis Jenkins, 21 Tavis Knoyle, 22 Gareth Davies, 23 Tom Isaacs