Cross comes in at tighthead prop for Euan Murray, who is unavailable for this weekend's match as a result of his Christian faith.
Meanwhile on the replacements bench, Dougie Hall has recovered from the knee injury that he sustained against England and is restored as the Scots' reserve hooker.
His Glasgow Warriors team-mate, prop Jon Welsh, also wins a place on the bench, his first involvement in a matchday 23 since he returned home early from last summer's tour to the South Pacific to undergo shoulder surgery.
Alastair Kellock will become the 34th Scot to reach the landmark of 50 caps for his country if he is introduced from the bench.
Scotland interim head coach Scott Johnson said: "We have to improve on our last game and that's been our theme at training all week.
"I make no apology for saying again that we have to step up our work in the contact area. Yes, we've some talented athletes in the squad, but we have to give them the opportunities.
"It's good to see players challenging for selection - and there are a number consistently putting their hands up, which is exactly what we want to see.
"But we've kept changes to a minimum and are saying to the players, 'You've won one game. Now go out show us you can win another'."
Just over 1,800 tickets remain for Sunday's Scotland v Ireland match. They can be bought via the 24-hour credit card hotline 0844 335 3933, via www.scottishrugby.org, or in person from the Ticket Centre at Murrayfield Stadium.
SCOTLAND Team & Replacements (v Ireland, 2013 RBS 6 Nations Championship, Murrayfield, Sunday, February 24, kick-off 2pm):
Club/International Caps -
15. Stuart Hogg (Glasgow Warriors/12)
14. Sean Maitland (Glasgow Warriors/2)
13. Sean Lamont (Glasgow Warriors/73)
12. Matt Scott (Edinburgh/9)
11. Tim Visser (Edinburgh/7)
10. Ruaridh Jackson (Glasgow Warriors/17)
9. Greig Laidlaw (Edinburgh/15)
1. Ryan Grant (Glasgow Warriors/7)
2. Ross Ford (Edinburgh/65)
3. Geoff Cross (Edinburgh/18)
4. Richie Gray (Sale Sharks/29)
5. Jim Hamilton (Gloucester/43)
6. Robert Harley (Glasgow Warriors/2)
7. Kelly Brown (Saracens/54) (capt)
8. Johnnie Beattie (Montpellier/18)
16. Dougie Hall (Glasgow Warriors/40)
17. Jon Welsh (Glasgow Warriors/1)
18. Moray Low (Glasgow Warriors/16)
19. Alastair Kellock (Glasgow Warriors/49)
20. David Denton (Edinburgh/11)
21. Henry Pyrgos (Glasgow Warriors/5)
22. Duncan Weir (Glasgow Warriors/2)
23. Max Evans (Castres Olympique/34)