Richie is named at No.8 alongside Heriot's and National Academy flanker Chris Fusaro who will make his first start for the Warriors. The team will be led by scrum-half Mark McMillan.
Speaking about his rejuvenated No.8, head coach Sean Lineen said: "To get Richie back is fantastic. He's a quality player and is desperate to play and that's what you want. There are some guys who err on the side of caution whereas Richie came up and said 'I want to play'."
On the third man to captain the Warriors so far this season, Sean added: "Mark wears his heart on his sleeve. I think he's a great lad and you'll certainly hear him out there tomorrow night. He's done a great job for us all season."
Cardiff currently trail the Warriors by 12 points in the Magners League, however, Sean is expecting a fierce encounter at Firhill as he refuses to believe that their league position reflects the true strength of their squad.
"Cardiff are a tough team. You look at where they are in the league, it doesn't do the quality of their squad justice and they're going to come at us all guns blazing."
14 Hefin O'Hare
13 Max Evans
12 Peter Horne
11 DTH van der Merwe
10 Ruaridh Jackson
9 Mark McMillan CAPTAIN
1 Jon Welsh
2 Dougie Hall
3 Moray Low
4 Tim Barker
5 Richie Gray
6 James Eddie
7 Chris Fusaro (Heriot's)*
8 Richie Vernon
Substitutes
16 Fergus Thomson
17 Kevin Tkachuk
18 Dan Turner
19 Paul Burke (Ayr)
20 Colin Gregor
21 Alex Dunbar (Selkirk)*
22 Peter Murchie
* = Member of Scottish Rugby's National Academy