Prop Tomas Francis will make his international debut but will be surrounded by a vastly experienced pack, with Gethin Jenkins and Ken Owens joining him in the front-row, Bradley Davies and captain Alun-Wyn Jones in the second-row and British and Irish Lions trio Dan Lydiate, Justin Tipuric and Taulupe Faletau behind them.
Ospreys duo Rhys Webb and Dan Biggar continue their halfback partnership with Jamie Roberts and Scott Willams named in the midfield.
Winger George North, winning his 50th cap, is back for his first game since suffering concussion in March, with Alex Cuthbert and Leigh Halfpenny completing the back line.
"We have trained well over the past few weeks and Saturday is a chance for a lot of players to get their first taste of rugby this campaign," Gatland said in a statement.
"We trimmed the squad down in the middle of August and the remaining 38 have worked extremely hard."
Gatland will need to announce his final World Cup squad of 31 by next Monday (local time).
Wales team to play Ireland
15-Leigh Halfpenny, 14-Alex Cuthbert, 13-Scott Williams, 12-Jamie Roberts, 11-George North, 10-Dan Biggar, 9-Rhys Webb; 8- Taulupe Faletau, 7-Justin Tipuric, 6-Dan Lydiate,5-Alun Wyn Jones (captain), 4-Bradley Davies, 3-Tomas Francis, 2-Ken Owens, 1-Gethin Jenkins.
Replacements: 16-Scott Baldwin, 17-Paul James, 18-Aaron Jarvis, 19-Luke Charteris, 20-James King, 21-Gareth Davies, 22-Rhys Priestland, 23-Hallam Amos.
