Perpignan beat Grenoble 38-13 on Sunday to secure automatic promotion to the French Top 14 after four years.
Perpignan, who won the most recent of their seven French titles in 2009, struck early when Jonathan Bousquet touched down in the fourth minute. They led 14-13 at half time in Toulouse.
Perpignan who finished top of the Pro D2 standings pulled away from Grenoble, who came third, with 24 points between the 52nd and 72nd minutes.
Bousquet, who kicked a penalty as well as converting all five tries, finished with 18 points.
Grenoble, relegated from the top flight last season, have a second chance to gain promotion. They face Oyonnax, who finished 13th in the Top 14, in a playoff next Saturday.
Perpignan's supporters cheer their team in Toulouse southern France