O'Donoghue, who touched down twice against the Scots, will reprise his back row partnership with fellow try scorer Peadar Timmins and team captain Dan Leavy.
Vice-captain Ross Byrne kicked 14 points in the opening game and retains the number 10 jersey. He will again be partnered at half-back by the impressive Nick McCarthy.
There are three further changes on the replacements bench with Sean McNulty replacing Jacob Walshe, Denis Coulson replacing Shane Delahunt and Frankie Taggart taking over from Rory Moloney.
Ireland Under-20 head coach Mike Ruddock commented: "We got off to a good start in difficult conditions against the Scots but the Welsh will provide a much sterner test.
"An (almost) unchanged side gives us some consistency and will allow combinations to develop across the field.
"We have some fresh faces on the bench which will be hoping to make an impact on the game at some stage."
Friday's second fixture of the U-20 Championship will be broadcast live on RTÉ Two and rte.ie/live (island of Ireland only).
Match tickets can be purchased in advance at either Buccaneers RFC or the Bounty. They can also be bought at the turnstiles on match night, but do come along early especially as pyrotechnics prior to kick-off will add to the fantastic atmosphere.
Stand seats generally sell out in advance of each match. Ticket prices are as follows: Stand €20; Terrace €15; Children/OAP €5; Family (two adults and two children to ground) €30.
Group discounts are available to clubs/schools, etc., as are a limited number of pre-match tables where you can enjoy a three-course meal with wine and have a reserved seat in the stand for only €40 per person.
Contact Buccaneers administrator Geraldine 0861732711 (during office hours) or email email@example.com.
IRELAND UNDER-20 Team & Replacements (v Wales Under-20s, 2014 RBS Under-20 6 Nations Championship, Dubarry Park, Friday, February 7, kick-off 7.35pm):
15. David Busby (Queen's University/Ulster)
14. Cian Kelleher (Lansdowne/Leinster)
13. Garry Ringrose (UCD/Leinster)
12. Peter Robb (Old Belvedere/Leinster)
11. Ian Fitzpatrick (Lansdowne/Leinster)
10. Ross Byrne (UCD/Leinster)
9. Nick McCarthy (UCD/Leinster)
1. Peter Dooley (Lansdowne/Leinster)
2. Max Abbott (Cork Constitution/Munster)
3. Rory Burke (Cork Constitution/Munster)
4. Sean O'Brien (Galwegians/Connacht)
5. Ross Molony (UCD/Leinster)
6. Peadar Timmins (UCD/Leinster)
7. Dan Leavy (UCD/Leinster) (capt)
8. Jack O'Donoghue (UL Bohemians/Munster)
16. Sean McNulty (UCD/Munster)
17. Denis Coulson (Lansdowne/Leinster)
18. Oisin Heffernan (Lansdowne/Leinster)
19. Joe Joyce (Bristol/Exiles)
20. Frankie Taggart (Belfast Harlequins/Ulster)
21. Jack Cullen (Bruff/Munster)
22. Conor McKeon (Lansdowne/Leinster)
23. Dan Goggin (Young Munster/Munster)
IRELAND'S RBS UNDER-20 6 NATIONS FIXTURES/RESULTS:
IRELAND Under-20s 34 Scotland Under-20s 7
Friday, January 31
IRELAND Under-20s v Wales Under-20s
Dubarry Park, 7.35pm
Friday, February 7
England Under-20s v IRELAND Under-20s
Franklin's Gardens, Northampton, 6.15pm
Saturday, February 22
IRELAND Under-20s v Italy Under-20s
Dubarry Park, 7.05pm
Friday, March 7
France Under-20s v IRELAND Under-20s
Stade Maurice Trélut, Tarbes, 8.55pm local time/7.55pm Irish time
Friday, March 14