Williams has not featured for Blues since mid-October but, after recovering from injury suffered during the autumn internationals, is named in the starting line-up as Blues look to keep cup hopes alive.
Director of Rugby Phil Davies rings the changes for the cup clash and gives many of his young stars the chance to shine in the Pool 2 encounter.
Owen Williams is paired with Dafydd Hewitt in midfield while Tom Williams is called up for a wing berth. Dan Fish is named at full back while Simon Humberstone and Lewis Jones combine at half back.
Flanker Ellis Jenkins will captain the side from the back row alongside Rory Watts-Jones and Luke Hamilton at Number Eight.
James Down is selected in the second row while a new-look front row will see prop Thomas Davies and hooker Rhys Williams pack down alongside Benoit Bourrust.
Loosehead prop Lewis Smout and Academy front row Callum Lewis are named among the replacements with Ben Roach who could make his Blues debut.
Captain Jenkins said: “The LV=Cup is all about youngsters stepping up and trying to make an impression. It’s a good opportunity for people to step up and hopefully claim a jersey than going forward into the league games.
“Obviously we want to win this game on the weekend. We are looking for a good performance from some youngsters and hopefully we can make a good impression.
“Bath are a good team with a big squad,” he added. “They will have had a number of international call ups, so we don’t know what kind of team will be playing, but whatever team they pick it will be a big side. We will have to step up to the mark.”
Cardiff Blues: 15 Dan Fish, 14 Tom Williams, 13 Owen Williams, 12 Dafydd Hewitt, 11 Chris Czekaj, 10 Simon Humbersone, 9 Lewis Jones; 1 Thomas Davies, 2 Rhys Williams, 3 Benoit Bourrust, 4 Chris Dicomidis, 5 James Down, 6 Rory-Watts Jones, 7 Ellis Jenkins (c), 8 Luke Hamilton
Replacements: 16 Kristian Dacey, 17 Lewis Smout, 18 Callum Lewis, 19 Miles Normandale, 20 Ben Roach, 21 Lloyd Williams, 22 Gavin Evans, 23 Owen Jenkins