Jennings forms an exciting looking back row combination with recent RBS 6 Nations debutants Kevin McLaughlin and Sean O'Brien.
Devin Toner lines up at lock alongside Malcolm O'Kelly who will be making his 177th Leinster appearance this weekend.
Bernard Jackman has been pencilled in at hooker, with Stan Wright and CJ van der Linde taking the prop berths.
Eoin Reddan partners Jonathan Sexton at half-back and Shane Horgan (175th cap) and full-back Girvan Dempsey (167th) have been named in the back-three alongside Bank of Ireland Leinster Player of the Month Isa Nacewa.
Andrew Conway, who has impressed for the Ireland Under-20s this season, could make his Leinster debut as a replacement.
Over 14,500 tickets have been sold for Saturday's Magners League game against the Scarlets. There will be the usual 'Family Day' activity on the day and musician Colm Lynch will be performing at half-time.
Meanwhile, the Wales trio of Martin Roberts, Jonathan Davies and Ken Owens will all start for the Scarlets at the RDS on Saturday.
After Leinster did the double on the Scarlets in the Heineken Cup in December, Nigel Davies' side will be looking to gain revenge and some valuable Magners League points in their bid to climb the table and secure a place in Europe next season.
The Scarlets beat the reigning European champions 18-16 in the opening Magners League game of the season back in early September at Parc y Scarlets.
Roberts starts at scrum half, with the exciting centre partnership of Jonathan Davies and Regan King reunited for the first time in a year. King starts in his second game for the Welsh region after returning from a long term hamstring injury.
Young Llanelli back Dan Newton will make his first start for the region at full-back. The 20-year-old has impressed the boot in recent games in the Welsh Premiership with Llanelli RFC. Daniel Evans moves from full-back to the right wing.
Experienced Australian international David Lyons captains the side for the away fixture, with 50 games for the region now under his belt.
LEINSTER: Girvan Dempsey, Shane Horgan, Fergus McFadden, Shaun Berne, Isa Nacewa; Jonathan Sexton, Eoin Reddan; Stan Wright, Bernard Jackman, CJ van der Linde, Devin Toner, Malcolm O'Kelly, Kevin McLaughlin, Shane Jennings (capt), Sean O'Brien.
Replacements: Richardt Strauss, Mike Ross, Trevor Hogan, Stephen Keogh, Paul O'Donohoe, Eoin O'Malley, Andrew Conway.
SCARLETS: Dan Newton; Daniel Evans, Regan King, Jonathan Davies, Andy Fenby; Rhys Priestland, Martin Roberts; Iestyn Thomas, Ken Owens, Deacon Manu, Dominic Day, Damian Welch, Rob McCusker, Johnathan Edwards, David Lyons (capt).
Replacements: Phil John, Emyr Phillips, Rhys Thomas, Vernon Cooper, Josh Turnbull, Tavis Knoyle, Gareth Maule.
Referee: Andy Macpherson (Scotland)
Assistant Referees: Colin Stanley, Jonathan Peak (both Ireland)
Television Match Official: Tony Redmond (Ireland)
Match Odds (Paddy Power): Leinster to win: 1/9; Draw: 25/1; Scarlets to win: 5/1
Pre-Match Quotes: Michael Cheika (Leinster) - "The only player who is a long term doubt is Luke Fitzgerald and he wouldn't have been in the national team anyway, so it is probably about a good a compliment as we could have at this stage of the season," he said.
"Kevin McLaughlin, Sean O'Brien, Shane Jennings, Eoin Reddan and Jonathan Sexton will all be involved (this weekend).