The two sides met in a pulsating semi-final last year, with the French side producing an outstanding showing to fight back and secure victory.
A red-hot Leinster will nonetheless be confident of winning a fifth crown, and fans will travel in good number to Marseille for a late May weekend in the French south-coast sun.
Ronan O’Gara, long-time foe of Leinster during his time as Munster fly-half, is head coach of La Rochelle, who have never won a major trophy.
Here’s everything you need to know ahead of the final:
When and where is it?
Leinster vs La Rochelle in the final of the Champions Cup will be held at the Stade Velodrome in Marseille, France, kicking off at 4.45pm BST on Saturday 28 May.
How can I watch it?
Viewers in the United Kingdom can watch the final live on Channel 4 or BT Sport 2. Coverage on the terrestrial channel begins at 4.15pm BST, while BT Sport’s coverage starts at 4pm. The game will be streamed on All4, while BT Sport subscribers can also watch via the app or online player.
Tadhg Furlong and James Lowe have both been dealing with niggly injuries, but are fit to play for Leinster. Ronan Kelleher has come through return-to-play protocols and starts at hooker, while Ciaran Frawley has recovered from a facial injury to begin on the bench in a settled matchday 23.
La Rochelle are without two former All Blacks in scrum-half Tawera Kerr-Barlow, who has not recovered sufficiently from a broken hand, and back-row Victor Vito, who is ruled out by an ankle injury. They are replaced by Thomas Berjon and Matthias Haddad. Brice Dulin and Will Skelton are able to return, and start at full-back and in the second row.
Leinster XV: H Keenan; J O’Brien, G Ringrose, R Henshaw, J Lowe; J Sexton, J Gibson-Park; A Porter, R Kelleher, T Furlong; R Molony, J Ryan; C Doris, J van der Flier, J Conan.
Replacements: D Sheehan, C Healy, M Ala’alatoa, J McCarthy, R Ruddock; L McGrath, R Byrne, C Frawley.
La Rochelle XV: B Dulin; D Leyds, J Sinzelle, J Danty, R Rhule; I West, T Berjon; D Priso, P Bourgarit, U Atonio; T Lavault, W Skelton; W Liebenberg, M Haddad, G Alldritt.
Replacements: F Bosch, R Wardi, J Sclavi, R Sazy, R Bourdeau; A Retiere, L Botia, J Favre.
La Rochelle 7/2
Leinster secure their fifth European crown with a strong performance. Leinster 30-17 La Rochelle