The inclusion of Darge, who will lead the team alongside Finn Russell, and Gilchrist comes on the back of news that Luke Crosbie and Richie Gray will miss the remainder of the championship through injury.
Fresh from a thrilling try brace in the opening week victory against Wales, Duhan van der Merwe joins fellow winger Kyle Steyn and full-back Kyle Rowe in the back three positions.
Sione Tuipulotu, named vice-captain again, forms a centre pairing with Huw Jones for the seventh consecutive championship match.
Russell and Ben White remain the starting half-backs, the former having landed 12 points from the tee in Cardiff one matchday one.
Pierre Schoeman, who scored a fourth Scotland try last weekend, will occupy the loosehead prop berth, with Zander Fagerson again named at tighthead and George Turner completing the front row from hooker.
Gilchrist joins forces with Scott Cummings in the second row, with Matt Fagerson shifting to blindside flanker and Jack Dempsey at number 8 to complete a back row completed by openside flanker Darge.
Propping duo Alec Hepburn and Elliot Millar-Mills, fresh from making their Scotland debuts against Wales, are once more named among the replacements, as are Ewan Ashman and Sam Skinner. Back row forward Andy Christie is poised for his first Six Nations action since facing the same opposition in 2022.
Scotland's squad is rounded off with back division options by way of scrum-half George Horne, Ben Healy (stand-off) and centre Cameron Redpath.
Scotland
15 Kyle Rowe - Glasgow Warriors (2)
14 Kyle Steyn - Glasgow Warriors (16)
13 Huw Jones - Glasgow Warriors (44)
12 Sione Tuipulotu - Vice-Captain - Glasgow Warriors (23)
11 Duhan van der Merwe - Edinburgh Rugby (35)
10 Finn Russell - Co-Captain - Bath Rugby (76)
9 Ben White - Toulon (19)
1 Pierre Schoeman - Edinburgh Rugby (27)
2 George Turner - Glasgow Warriors (41)
3 Zander Fagerson - Glasgow Warriors (63)
4 Grant Gilchrist - Edinburgh Rugby (68)
5 Scott Cummings - Glasgow Warriors (34)
6 Matt Fagerson - Glasgow Warriors (41)
7 Rory Darge - Co-Captain - Glasgow Warriors (15)
8 Jack Dempsey - Glasgow Warriors (16)
Substitute
16 Ewan Ashman - Edinburgh Rugby (13)
17 Alec Hepburn - Exeter Chiefs (1)
18 Elliot Millar-Mills - Northampton Saints (1)
19 Sam Skinner - Edinburgh Rugby (31)
20 Andy Christie - Saracens (4)
21 George Horne - Glasgow Warriors (27)
22 Ben Healy - Edinburgh Rugby (4)
23 Cameron Redpath - Bath Rugby (10)