Bristol held off a spirited Doncaster Knights fightback to end their long wait for promotion to the Premiership in a 60-47 aggregate victory.
Despite topping the regular-season standings for five of the past seven seasons in English rugby's second tier, Bristol have repeatedly failed to make it through the play-off process.
However, after a 28-13 win at Castle Park last week, Wednesday's 34-32 defeat at Ashton Gate was not enough to deny Andy Robinson's men, who have lost three finals since their relegation from the top flight in 2009.
Doncaster had threatened a revival when Will Hurrell went over late in the first half, yet Bristol's response through Will Cliff was immediate.
A disallowed try early in the second felt like the end of the visitors' challenge, but Bristol soon looked in danger of succumbing to a similar collapse to the one that cost them dear against Worcester Warriors last year, as Paul Jarvis, Tyson Lewis and Ollie Stedman crossed.
Bristol stopped the rot with six minutes left on the clock, James Phillips forcing his way over before Callum Sheedy added the extras, and Latu Makaafi's late try for Doncaster was of little consequence.
The match had to be delayed for a long period during the second half for an apparent head injury to Bristol's Olly Robinson.