The final change sees Lucas Amorosino called onto the wing with Argentine international team-mate Joaquin Tuculet ruled out of the game with a hand injury.
Manoa Vosawai returns among the replacements alongside prop Scott Andrews after his second half appearance for Wales in the 6 Nations victory over Italy.
Attack Coach Paul John said: "This game is important to us and we are looking forward to the challenge of going to the Kingspan.
"We need to apply ourselves to an important game and get the maximum points we can from the rest of this season.
"There are only a few weeks left and we want to finish on a high. It's important we have momentum and are positive for the rest of this season. Ulster is a difficult place to go but we are looking forward to the test."
Cardiff Blues: 15 Rhys Patchell, 14 Alex Cuthbert, 13 Cory Allen, 12 Gavin Evans, 11Lucas Amorosino, 10 Gareth Anscombe, 9 Lloyd Williams; 1 Sam Hobbs, 2 Matthew Rees (c), 3 Adam Jones, 4 Jarrad Hoeata, 5 Lou Reed, 6 Josh Turnbull, 7 Ellis Jenkins, 8 Josh Navidi
Replacements: 16 Kristian Dacey, 17 Taufa'ao Filise, 18 Scott Andrews, 19 Macauley Cook, 20 Manoa Vosawai, 21 Tavis Knoyle, 22 Gareth Davies, 23 Tom Isaacs
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