The 28-year-old openside specialist has signed a two-year deal after a series of impressive performances since joining in January. He has scored seven tries in nine games for Bristol, to help them to the top of the Greene King Championship and establish them as favourites for promotion to the Aviva Premiership.
Rennie's move was brokered by Andy Robinson, the former Scotland coach and now director of rugby at the club, for whom he also played when he made his breakthrough at Edinburgh a few years ago. "His professionalism and consistency in his performances during a relatively short time at the club have helped to drive the quality and standards of the squad," said Robinson.
Intriguingly, one of Rennie's rivals for the No.7 shirt at Bristol will be Robinson's 22-year-old son Oliver, a former England under-18 player who has also just committed to the club. Robinson Jnr joins from Moseley, where he has been a first-team regular for the past two seasons.
Rennie joins a long list of Scottish players whose departures have been confirmed during the stewardship of Alan Solomons, the South African head coach who has been heavily criticised for appearing to favour his own countrymen rather than local talent in his selections.
In recent months, Greig Laidlaw, Nick De Luca and Geoff Cross have announced they are leaving the side. Lee Jones is on loan to Glasgow while Gregor Hunter and Harry Leonard have been cut from the squad. Edinburgh have confirmed, though, that Stuart McInally, the flanker who is learning to play at hooker, is to return to the club at the end of his loan deal with Bristol.
Glasgow have confirmed that Byron McGuigan, the Namibian-born utility back who has spent the past two seasons at Scotstoun, is to leave the club at the end of this campaign.