The 27-year-old flanker skippers a side at the Stade de France showing 12 changes to the starting XV that annihilated Pool B whipping boys Romania 84-0 last weekend.
Ritchie had to sit that game out after taking a knock to the head in their previous match, another hefty win over Tonga.
Among those returning is Blair Kinghorn at full-back, which takes him to the 50-cap milestone.
Winger Darcy Graham retains his place after scoring four tries in the hammering of Romania.
Sione Tuipulotu and Huw Jones resume a familiar starting centre partnership which has enjoyed nine outings in 2023.
As part of a half-back pairing that will combine to pass 140 caps on Saturday, scrum-half Ali Price gets the nod to partner stand-off Finn Russell.
The Scots have to win to entertain any chance of reaching the last eight - they are five points adrift of defending champions South Africa and four behind the Irish.
Ireland will start hot favourites as they are on a record run of 16 successive Test victories, including an impressive 13-8 victory over the Springboks in the pool match a fortnight ago.
The Scots, who lost to South Africa in their opening pool game, have been beaten by Ireland in their past eight meetings.
Team (15-1)
Blair Kinghorn; Darcy Graham, Huw Jones, Sione Tuipulotu, Duhan van der Merwe; Finn Russell, Ali Price; Jack Dempsey, Rory Darge, Jamie Ritchie (capt); Grant Gilchrist, Richie Gray; Zander Fagerson, George Turner, Pierre Schoeman
Replacements: Ewan Ashman, Rory Sutherland, WP Nel, Scott Cummings, Matt Fagerson, Luke Crosbie, George Horne, Ollie Smith
Coach: Gregor Townsend (SCO)
