The 29-year-old has become a fixture in the midfield for both club and country since making his Glasgow Warriors debut in a 31-19 win over the Ospreys in November 2015, scoring 10 tries in Glasgow colours to date.
Johnson lines up in a starting XV showing three changes from last weekend's 17-11 victory over Ulster, a result that propelled Franco Smith's team into the top four of the BKT URC standings.
An unchanged front-row sees Johnny Matthews continue at hooker, packing down between Nathan McBeth - who lines up against his former team for the first time - and Argentinian international Lucio Sordoni.
The back-row sees Sione Vailanu shift to number eight in a combination that sees two alterations from last weekend's victory; Ally Miller comes in at blindside to make his first appearance of the 2022/23 campaign, whilst Rory Darge is named at openside for his first outing since picking up a knee injury against Cardiff back in round two of the BKT URC.
Johnson lines up at inside centre on the occasion of his 100th appearance, joining captain Stafford McDowall - himself making his 50th appearance in Glasgow colours - in the midfield for the trip to Emirates Airline Park.
After impressing in the FOSROC Super6 since its inception, Elias Caven will make his professional debut for Glasgow Warriors after being named on the wing, the Ayrshire Bulls standout joining Cole Forbes and Josh McKay in the back-three.
Allan Dell could also make his club debut after the Scotland prop was named amongst the replacements for tomorrow afternoon's match, having recovered from a calf injury sustained in pre-season to take his place in the matchday 23 for the first time.
Speaking following selection, Head Coach Smith told glasgowwarriors.org: "Tomorrow is an opportunity for us to show the progression we have made across this season so far.
"To be a great team you need to be a great squad, and the 23 players we have selected know that they represent everyone at this club when they run out onto the field.
"I would also like to congratulate Sam on his 100th appearance for the club - he is someone who always gives everything he has to the team and sets a strong example to his team-mates."
15 Josh McKay (25)