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.
Tickets are on sale here and from Ticketmaster outlets nationwide. Tickets can also be purchased in Donnybrook from Spar and the Leinster Rugby Store and tickets will be available outside the RDS from 3pm on Saturday.
LEINSTER (v Scarlets): 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.