Bristol won the Championship title and were promoted back to the Premiership after second-placed Ealing Trailfinders were beaten 50-19 at Doncaster.
After a 60-17 triumph at Nottingham on Friday, Bristol knew they would be champions if Ealing failed to win.
And the result left Pat Lam's side 18 points clear at the top, with Ealing only able to earn 15 more points.
Bristol were promoted through the play-offs in 2015-16, but were relegated from the Premiership last season.
They will have finished top of the regular-season table in each of the last four seasons they have been in the Championship.
Ealing, meanwhile, will remain in the second tier next term as the play-offs were scrapped in favour of automatic promotion for the league winners.
Head coach Lam told BBC Radio Bristol: "I'm extremely proud, for all the players, the management, the staff, the board, the Lansdowns and all Bristol people.
"Although people say it was a formality, you have to work hard for it, so I'm pleased that we're heading up and we continue on the journey towards getting Champions Cup rugby.
"This is only part of the journey, it's only the first step. We've just done the first part but there's a long way to go to get where we want to get to."
He took charge last summer after Mark Tainton ended last season as acting head coach following the departure of Andy Robinson in November 2016.
"All the games have been extremely tough, because we have gone in to all the games as favourites," Lam added.
"We were gutted to lose at Jersey because we let an unbeaten season go, but we bounced back from that. When we've needed to, the boys dug deep. We've shown tremendous character at times and that'll hold us in good stead going forward."