Gaëtan Charbonnier struck twice at the Stade Francis-Le Blé to bring his season tally to 27, lifting him beyond Metz's Habib Diallo as the outright top scorer in Domino's Ligue 2 this campaign.
The result took Brest onto 74 points - four clear of third-place ESTAC Troyes with only three points left to play for.
Charbonnier's 27 goals this season are a career-best.
"We'll enjoy the moment," said coach Jean-Marc Furlan after sealing the fourth promotion of his managerial career. "After that, I'm sure Ligue 1 Conforama is wonderful, when you win matches. I'm very happy for the boys."
'Close to my heart'
Furlan has been getting linked with the vacant AJ Auxerre job - Cédric Daury is the interim coach at the Stade de l'Abbé-Deschamps - but he may not be ready to get off the emotional Brest rollercoaster quite yet.
"We'll decide after the Metz match next week," he said. "For the first time in my career, I'm in demand. But I've experienced a bond here like never before. We've got an exceptional relationship which is close to my heart."
Furlan's fourth promotion - and his favourite?
Nothing if not derserved
Furlan has a talented bunch of players with which to tackle the coming top-flight campaign. As well as the free-scoring Charbonnier, academy graduate Mathias Autret has enjoyed his best season to date, the 28-year-old midfielder chipping in with nine goals and eight assists; while France U21 goalkeeper Gautier Larsonneur has kept 13 clean sheets.
Franck Ribéry, David Ginola and Paul Le Guen are a few greats of the game whose careers have passed through Brest, although Les Ty' Zefs have only played four previous seasons in the French top flight.