Perpignan head coach Patrick Arlettaz said his players need to "sweat and bleed" if they want to stay in the French Top 14 next season after winning promotion thanks to Saturday's 33-14 win over Biarritz.
Fiji fly-half Ben Volavola crossed as did former New Zealand sevens winger George Tilsley and young full-back Melvyn Jaminet scored the other 23 points to seal a return to the top flight after relegation in 2019.
The Basques will have a second chance against the 13th-place finisher in the Top 14 in next weekend's play-off.
"There was a lot of pressure. What the players have done is massive," Perpignan coach Patrick Arlettaz said.
"We all know the extreme difficulty of the Top 14. How it is ruthless and hard. We still have hope that with work, selflessness, sweat, blood, tears we can maybe stay up," he added.
Perpignan, who had former New Zealand fly-half Dan Carter on their books in 2009, named Volavola inside Argentina centre Jeronimo de la Fuente.
Former England No. 8 Steffon Armitage captained Biarritz, who beat Vannes in last weekend's semi-final.
The Catalans led 16-9 at the break after Tilsley's early effort and Jaminet's efforts from the tee. Irish scrum-half James Hart kicked three penalties for Biarritz.
Early in the second half, Biarritz lost centre Francis Saili, who won two All-Black caps in 2013, to a yellow card for a deliberate knock on and within two minutes Volavola scored.
Jaminet added a third try with six minutes left before hooker Lucas Peyresblanques claimed a consolation effort for the five-time Top 14 champions.
Biarritz, who last played in the first division in 2014, will play Pau or Bayonne next Saturday, depending on which side finishes in 13th place after Saturday's final round of Top 14 games.