Jennings forms a back row unit which includes Kevin McLaughlin and Stephen Keogh, with Malcolm O'Kelly locking down alongside Devin Toner.
CJ van der Linde starts at tighthead prop in a front row that includes Bernard Jackman and Stan Wright.
Reddan partners Shaun Berne at half-back, with Isa Nacewa named on the left wing.
The experienced Girvan Dempsey and 18-year-old Andrew Conway, who comes in for his first senior start for the province, complete the back-three.
Ireland Under-20 captain Rhys Ruddock is named amongst the replacements alongside the likes of Ireland internationals Trevor Hogan and Mike Ross.
Looking ahead to Sunday's meeting with the Blues, the Australian-born Berne believes that the game will present an opportunity for every member of the squad to stake a claim ahead of a crucial month in the Magners League.
"Even though we won last time out against Cardiff at the RDS, Sunday's game will be a real test for us coming, as it does, when so many of our players are away on international duty," he said.
"At this time of year, the squad's resources are stretched, but with a few of the international players returning, we're in a good frame of mind ahead of the game.
"Having played Cardiff twice before with Bath, you know what to expect against them, or any Welsh side for that matter - pride, physicality and a high skill level.
"They're a passionate rugby playing people and rugby's pretty much a national past-time over there.
"From a player's perspective it's a great place to play and with the new stadium and a good surface to play on it should make for an exciting game."
He added: "Even though we have big games coming up this month in the Magners League, we'll take it one game at a time and we're not looking beyond this challenge.
"For those of us who want to play regularly in the side as we approach the business end of the season, Sunday will present an opportunity to stake a claim.
"As well as the pride in representing Leinster, the Ireland players who have been released this week will no doubt look to Jonathan Sexton's example last month when a good showing against the Scarlets helped him earn a spot in the win over England last weekend.
"It's imperative that we begin well and look to dominate the key exchanges and if we manage that, we'll need to be playing at the top of our game to get the win."
LEINSTER (v Cardiff Blues): Girvan Dempsey; Andrew Conway, Eoin O'Malley, Fergus McFadden, Isa Nacewa; Shaun Berne, Eoin Reddan; Stan Wright, Bernard Jackman, CJ van der Linde, Devin Toner, Malcolm O'Kelly, Kevin McLaughlin, Shane Jennings (capt), Stephen Keogh.
Replacements: Richardt Strauss, Mike Ross, Trevor Hogan, Rhys Ruddock, Paul O'Donohoe, Ian Madigan, Simon Keogh.