The Scotland international flanker played in every PRO12 game last season as the Warriors reached the final, with tomorrow night's opponents Leinster beating them 34-12 in the showpiece event in May.
Peter Murchie, who has played in both of the Warriors pre-season fixtures, continues at full-back, with Tommy Seymour and Lee Jones on either wing.
Mark Bennett and Alex Dunbar form the centre partnership, with Peter Horne at stand-off and Henry Pyrgos at scrum-half.
Alex Allan makes his competitive debut for the club at loose-head, after joining from Edinburgh, while Fraser Brown has been handed his first start in a Glasgow shirt at hooker. Euan Murray is named at tight-head, after the Scotland prop returned to Glasgow in the summer.
Fijian Leone Nakarawa and Scotland cap Jonny Gray will combine in the engine room.
Harley is at blindside, Chris Fusaro is at openside and Josh Strauss will lead the team from number 8, in the absence of club captain Al Kellock, who is recovering from injury.
Stuart Hogg and Sean Lamont are both included on the Warriors bench after their involvement at the Commonwealth Games in July.
More than 5,000 tickets have been sold for tomorrow night's game, but standing tickets in the terrace are still available priced at £15 for adults, £10 for students and £5 for under-18s in advance from www.glasgowwarriors.org.
Adult and concession tickets will increase by £5 on matchday and tickets will be available at the stadium from 1pm (subject to availability).
Glasgow Warriors head coach Gregor Townsend said: "We're looking forward to hosting the defending champions at Scotstoun tomorrow night in front of our own supporters.
"It was a great achievement for the club to reach the PRO12 Final in May, but ultimately we were disappointed to lose, although it was a very close game up until the final quarter.
"This is now a new season and a fresh start for all the clubs and we know we'll have to be at our very best to get a positive result tomorrow.
"Our games with Leinster have always been very tight and competitive and we're expecting another big test against a top quality side.
"I'd like to congratulate Rob Harley, who is set to make his 100th appearance for the club tomorrow night. He's been ever consistent for us over the last few years and thoroughly deserves to join our group of centurions."
Glasgow Warriors team to play Leinster, GUINNESS PRO12, Scotstoun Stadium, Saturday 6 September (kick-off 5.15pm) - live on Sky Sports 1:
15. Peter Murchie
14. Tommy Seymour
13. Mark Bennett
12. Alex Dunbar
11. Lee Jones
10. Peter Horne
9. Henry Pyrgos
1. Alex Allan
2. Fraser Brown
3. Euan Murray
4. Leone Nakarawa
5. Jonny Gray
6. Rob Harley
7. Chris Fusaro
8. Josh Strauss (Captain)
Replacements
16. Pat MacArthur
17. Gordon Reid
18. Rossouw de Klerk
19. Tim Swinson
20. Adam Ashe
21. Niko Matawalu
22. Stuart Hogg
23. Sean Lamont
Not available due to injury: Connor Braid (head), Mike Cusack (medical/illness), Ryan Grant (shoulder), Dougie Hall (arm), Tyrone Holmes (trunk), Al Kellock (shoulder), Finn Russell (shoulder), Tom Ryder (knees), DTH van der Merwe (back), Richie Vernon (achilles), Duncan Weir (knee), Jon Welsh (shoulder) and Ryan Wilson (shoulder).
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland