Wales Under-20 ace Evans starts at fly half alongside scrum half Lloyd Williams, with Rhys Patchell missing the game as he continues his return to play protocols after suffering a concussion.
The other change in the backs is a call-up for Dan Fish at full back, with USA international Blaine Scully moving to the wing with Alex Cuthbert ruled out of the derby with minor knee strain.
Flanker Sam Warburton returns to the team, after missing the clash with Harlequins through illness, while Lou Reed is named in the second row.
Hooker Ethan Lewis comes onto the bench alongside Craig Mitchell, Gareth Davies and Tom Isaacs.
Josh Navidi, Cory Allen, Gareth Anscombe, Ellis Jenkins miss the game through injury while Matthew Rees serves a suspension.
Head Coach Danny Wilson said: "We're looking forward to the derby and the challenge we will face against the Ospreys at the Liberty Stadium on Saturday afternoon.
"The Ospreys have been in good form, have a talented squad and have secured some impressive results in recent games in Europe. But it's important we concentrate on our own performance in Swansea and look to improve on recent displays.
"I have been impressed by Jarrod (Evans) so far this season and he part of the future of Cardiff Blues so it is important he is given a chance to perform on this stage.
"We travel with a motivated squad keen to make amends after the game with Harlequins and there is no better place to do that than in a derby."
Cardiff Blues: 15 Dan Fish, 14 Blaine Scully, 13 Rey Lee-Lo, 12 Gavin Evans, 11 Tom James, 10 Jarrod Evans, 9 Lloyd Williams; 1 Gethin Jenkins (c), 2 Kristian Dacey, 3 Taufa'ao Filise, 4 Lou Reed, 5 James Down, 6 Josh Turnbull, 7 Sam Warburton, 8 Manoa Vosawai
Replacements: 16 Ethan Lewis, 17 Sam Hobbs, 18 Craig Mitchell, 19 Jarrad Hoeata, 20 Macauley Cook, 21 Tavis Knoyle, 22 Gareth Davies, 23 Tom Isaacs
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