Iyogun suffered an Achilles problem during the defeat at Exeter Chiefs back in January and has not played since.
But he is back on the bench for the trip to Ashton Gate.
Saints boss Phil Dowson has brought in several first-team regulars for their first appearance of the season.
Fin Smith and Tom James form the half-back combination, with captain Fraser Dingwall coming in at centre, allowing Tommy Freeman to move to the wing.
In the pack, there are starts for Trevor Davison, Alex Moon, who makes his 100th Saints appearance, and Alex Coles.
Iyogun is part of a strong set of replacements, which include Juarno Augustus, James Ramm and George Furbank.
As for Bristol, they hand a debut to Benhard Janse van Rensburg.
The centre returns from injury to take his place in the midfield alongside James Williams, while Harry Randall and AJ MacGinty return at half-back.
In the pack, Harry Thacker and Max Lahiff come into the front row, with Ed Holmes partnering Josh Caulfield at lock and Joe Batley shifting to the blindside.
Magnus Bradbury makes his first appearance of the season at number eight, with Dan Thomas named at openside.
Bristol Bears: 15. Rich Lane; 14. Jack Bates, 13. Benhard Janse van Rensburg, 12. James Williams, 11. Gabriel Ibitoye; 10. AJ MacGinty, 9. Harry Randall (c); 1. Jake Woolmore, 2. Harry Thacker, 3. Max Lahiff; 4. Josh Caulfield, 5. Ed Holmes; 6. Joe Batley, 7. Dan Thomas, 8. Magnus Bradbury.
Replacements: 16. Will Capon, 17. Andrew Turner, 18. George Kloska, 19. James Dun, 20. Jake Heenan, 21. Kieran Marmion, 22. Callum Sheedy, 23. Joe Jenkins.
Saints: 15 George Hendy; 14 Tommy Freeman, 13 Fraser Dingwall (c), 12 Toby Thame, 11 Tom Seabrook; 10 Fin Smith, 9 Tom James; 1 Ethan Waller, 2 Curtis Langdon, 3 Trevor Davison, 4 Alex Moon, 5 Tom Lockett; 6 Alex Coles, 7 Angus Scott-Young, 8 Sam Graham.
Replacements: 16 Robbie Smith, 17 Emmanuel Iyogun, 18 Elliot Millar Mills, 19 Emeka Atuanya, 20 Juarno Augustus, 21 Archie McParland, 22 George Furbank, 23 James Ramm.