Grigg made his Warriors debut in March 2016 and has gone on to become a Scotland international through his impressive performances in a Warriors jersey.
He is joined in midfield by Stafford McDowall, both players have been selected as McCrea Financial Services Warrior of the Month nominees by the coaching staff off the back of their performances in November.
George Horne returns to the starting XV and will have Brandon Thomson outside of him.
Niko Matawalu has scored five tries in his last two games and starts again on the wing, Robbie Nairn is brought in to make his first start and home debut alongside Ruaridh Jackson in the back-three.
Alex Allan returns from Scotland camp to start at loose-head, with George Turner and D’Arcy Rae completing the front-row.
Tim Swinson starts having returned from injury off the bench last week and Scott Cummings is his partner in the engine room.
Chris Fusaro will captain the side from the outset for the first time since January 2014, while Matt Smith and Adam Ashe are also named in the back-row.
On the bench Siua Halanukonuka returns from injury to feature for the first time this season and winger Ratu Tagive is also included for the first time this campaign.
Glasgow Warriors Head Coach Dave Rennie said: “Winning is a habit and you want to keep doing that. Ultimately it is about performance, when I look back a few weeks ago we got beat by Munster but we played really well that night.
“We don’t like losing. It is all about the quality of how we play and we know if we can perform with that intensity and accuracy, we are going to win more than we lose.
“We have been going pretty well recently and know we have more in us, I want to see more of that tomorrow night.”
Glasgow Warriors team to play Scarlets in the Guinness PRO14 at Scotstoun Stadium, Saturday 1 December, kick-off 5.15pm – live on Premier Sports 1. You can follow the game on Twitter @GlasgowWarriors. Glasgow Warriors appearances in brackets:
1. Alex Allan (81)
2. George Turner (29)
3. D’Arcy Rae (50)
4. Tim Swinson (113)
5. Scott Cummings (45)
6. Matt Smith (21)
7. Chris Fusaro (C)
8. Adam Ashe (60)
9. George Horne (28)
10. Brandon Thomson (14)
11. Niko Matawalu (100)
12. Stafford McDowall (4)
13. Nick Grigg (49)
14. Robbie Nairn (1)
15. Ruaridh Jackson (143)
16. Kevin Bryce (15)
17. Oli Kebble (18)
18. Siua Halanukonuka (17)
19. Kiran McDonald (14)
20. Tevita Tamielau (2)
21. Nick Frisby (5)
22. Paddy Kelly (3)
23. Ratu Tagive (5)
Players unavailable due to injury: Zander Fagerson (ankle), Rory Hughes (shoulder), Sam Johnson (knee), Lee Jones (knee) and Lelia Masaga (calf).