Allen has not featured for Blues since the end of October after picking up a shoulder injury in the autumn internationals for Wales.
However, the talented rising star of Welsh rugby is now back to full fitness and is rewarded with a starting spot as Blues make a total of seven changes to the side that faced Zebre at the start of the month.
Wales wing Alex Cuthbert returns to the starting line-up, as Dan Fish moves to the full back slot, while scrum half Lloyd Williams also makes his comeback as he combines with Gareth Davies at half back.
A new-look front row will see Gethin Jenkins captain the team at loosehead prop and he will pack down with hooker Rhys Williams and Taufa’ao Filise, with the big Tongan tighthead prop making his first start of the calendar year.
The final change for Blues is the inclusion of back row Ellis Jenkins at openside flanker.
Attack Coach Paul John said: “It’s great to have Gethin Jenkins and Alex Cuthbert back in the starting line-up. Gethin will captain the team and has been great for us this week. Hopefully these guys will come in and give the team a real lift.
“The target until the end of the season is to perform well and get some wins. We want real positivity and the players to express themselves.
“We are looking forward to going down there and playing in Swansea. It’s a cracking stadium and hopefully it will be a big crowd to perform in front of too. It’s something to look forward to for all of us as we return to RaboDirect PRO12 action with a big derby day.”
Cardiff Blues: 15 Dan Fish, 14 Alex Cuthbert, 13 Cory Allen, 12 Gavin Evans, 11 Harry Robinson, 10 Gareth Davies, 9 Lloyd Williams; 1 Gethin Jenkins (c), 2 Rhys Williams, 3 Taufa’ao Filise, 4 Chris Dicomidis, 5 Filo Paulo, 6 Ellis Jenkins, 7 Josh Navidi, 8 Robin Copeland
Replacements: 16 Kristian Dacey, 17 Sam Hobbs, 18 Scott Andrews, 19 Lou Reed, 20 Macauley Cook, 21 Lewis Jones, 22 Simon Humberstone, 23 Isaia Tuifua