Scrumhalf Michael Ruru provided two assists to guide Vannes back to the Top 14 thanks to an 18-14 victory over Provence in French rugby's second-tier final on Saturday.
The 35-year-old New Zealander Ruru made his contributions on both sides of the interval as the Brittany side returned to the first division after just one season in Pro D2.
"It wasn't easy," said player of the match Ruru.
"We had a challenge this season, and today we turned up.
"We started from square one this season, and our objective was to be champions," he added.
Provence, coached by ex-France winger Philippe Saint-Andre, will have another shot at promotion when they face the Top 14's Perpignan in a play-off next Sunday.
The Bretons, who hammered Oyonnax and Ruru's younger brother Jonathan, 48-7 in last week's semifinal after finishing 21 points clear atop the table, led 10-7 at the break.
Ruru made his first assist of the game for France under-20s centre Robin Taccola after just five minutes before a conversion and a penalty from Maxime Lafage.
The southerners' response came from winger Paul Cellio after 26 minutes.
Vannes then claimed promotion with a quarter of an hour to play as English winger Ben Stevenson crossed, from another Ruru pass after Lafage had slotted a penalty.
Replacement scrumhalf Joris Cazenave converted his own try to claim Saint-Andre's side a late consolation.