Dave Rennie has made nine personnel changes to the starting XV for the visit of the defending champions, with new signing Aki Seiuli in line for a potential debut from the replacements bench.
Oli Kebble is the sole surviving member of the front-row from last weekend's trip to Exeter, as George Turner and D'arcy Rae come in to start.
Gray is partnered by fellow Scotland international Tim Swinson in the second-row, with the latter also returning to the starting lineup.
Robert Harley shifts from the second-row to the flank, lining up alongside Chris Fusaro and Ryan Wilson.
Ali Price makes his first start of the season at scrum-half, with Peter Horne starting outside him at fly-half.
Huw Jones comes into the side to start at outside centre, partnering Sam Johnson in the midfield for the first time this season.
Tommy Seymour moves to the wing to accommodate the returning Ruaridh Jackson at full-back, in a side completed by Nikola Matawalu.
Former Highlanders prop Seiuli is included in a matchday 23 for the first time since arriving at Scotstoun, with the man from Christchurch joined by Grant Stewart and Adam Nicol as the front-row replacements.
Kiran McDonald retains the 19 jersey from last weekend's trip to Exeter, as Adam Ashe comes into the squad as back-row cover.
Nick Frisby and Stafford McDowall also return to the squad, with Kyle Steyn completing the 23.
Speaking following the announcement, Rennie said: "It's good to have Ali back starting this weekend - he obviously had an extremely disappointing injury at the World Cup, and he's worked hard to get back to full fitness. He's had a couple of cameos off the bench, and he's ready to go.
"Leinster have great depth and have been the form team in the competition. They are very well coached, are playing with great confidence and have threats across the park. We'll need to be at our best to get a result.
"A packed Scotstoun is a special place to play at. The crowd are vocal and engaged and remind us that we're playing for something bigger than ourselves."
14 Tommy Seymour
13 Huw Jones
12 Sam Johnson
11 Nikola Matawalu
10 Peter Horne
9 Ali Price
1 Oli Kebble
2 George Turner
3 D'arcy Rae
4 Tim Swinson
5 Jonny Gray
6 Robert Harley
7 Chris Fusaro
8 Ryan Wilson (Captain)
Substitutes
16 Grant Stewart
17 Aki Seiuli
18 Adam Nicol
19 Kiran McDonald
20 Adam Ashe
21 Nick Frisby
22 Stafford McDowall)
23 Kyle Steyn
Not available due to injury: Siua Halanukonuka (calf), Scott Cummings (knee), Bruce Flockhart (knee), Jale Vakaloloma (shoulder), Callum Gibbins (shoulder), Sean Kennedy (foot), Lee Jones (calf), Ratu Tagive (hamstring) and DTH van der Merwe (knee)