It's a reward for the excellent form shown by 27 year old Delve this season when he has led Gloucester with distinction.
He has made 22 starts for the first team in competitive action, scoring two tries.
Saturday will be Delve's 10th cap and his first appearance in a Welsh jersey since the 2nd Test v South Africa in Pretoria on 14 June, 2008. It will also be his first start in the RBS 6 Nations.
Head Coach Warren Gatland said when announcing his side:
"Ryan has been managing his calf, but it has hampered his involvement in training and he needs to get it right for his own sake as well as for his region, who have some big matches of their own coming up, and for the sake of the national cause as we countdown to the World Cup."
"This is also a great opportunity for Gareth Delve, who we have been keeping a close eye on and who is also a leader himself. We feel we have a loose forward trio here who can be competitive."