Jonny Wilkinson's Toulon tasted Amlin Challenge Cup final defeat for the second time in three years as Dimitri Yachvili kicked Biarritz to victory.
Yachvili landed seven penalties from seven attempts to give the Basques their first European trophy.
Wilkinson responded with five penalties and a drop-goal for Toulon, who had prop Carl Hayman and flanker Steffon Armitage sin-binned in the second half.
Victory booked Biarritz's place in next season's Heineken Cup.
It will be the 13th consecutive year they have featured in the elite tournament, deserved reward for a club with a proud record in Europe.
Despite the riches of their millionaire president Mourad Boudjellal, Toulon's wait for a first trophy since their French Championship victory of 1992 goes on.
They will now turn their attention to the Top 14 play-offs, with a quarter-final play-off against Racing Metro next weekend.
Wilkinson will certainly not regard the Challenge Cup with any great affection. After three semi-final defeats with his old club Newcastle, he now has two final losses on his CV with Toulon, who were also beaten by Cardiff Blues in front of a partisan Marseille crowd in 2010.
The atmosphere was a little different at The Stoop, where a few thousand of either club's fans and a few thousand neutrals were treated to a dogfight typical of the French domestic league.
With intermittent rain falling during the opening period and neither side showing any ambition to move the ball wide, it developed into a battle of two left boots.
Yachvili, with a lazy swing that never looked liked missing, potted four out of four in the first half to nudge the Basques 12-9 ahead at the interval.
Wilkinson missed his first attempt after Toulon's scrummaging power made some inroads, but thereafter the former England fly-half banged over three of his own.
Biarritz were generally content to kick for the corners and attack the vulnerable Toulon line-out, where the imperious Imanol Harinordoquy was a dominant presence.
Armitage, the Top 14 player of the season, endured a frustrating evening, getting involved in a first-half skirmish with France centre Damien Traille and later earning a spell in the sin-bin for diving in the side of a ruck as Biarritz finally threatened a try.
There were precious few opportunities for either side to cross the whitewash, and on one of the rare occasions when space opened up for one of the wide men, Taku Ngwenya found Wilkinson's trademark defensive resolve firmly intact.
After Wilkinson had levelled matters early on after the resumption, the American winger found himself the victim of what appeared a tip-tackle from Hayman in the 46th minute.
The vociferous band of Biarritz supporters roared their disapproval as English referee Wayne Barnes brandished only a yellow card, Yachvili dispensing swift punishment to make it 15-12.
Seven minutes later Toulon were reduced to 13 men when Armitage was sin-binned and Yachvili again did the necessary to give Biarritz the luxury of a six-point lead for the first time in the match, only for Wilkinson to quickly bring Toulon within three again.
A brief outbreak of enterprise ended with Wilkinson bringing the scores level at 18-18 with a sweetly-struck drop-goal with 14 minutes left.
He did not quite have the distance with a penalty attempt from inside his own half moments later, and instead it was left to Yachvili to have the final say with six minutes left.
Toulon launched one last salvo, kicking a penalty to touch, winning the line-out and setting up camp on the Biarritz 22.
But with Wilkinson sitting back in the pocket waiting for the opportunity to send the game into extra-time, the Toulon pack conceded a penalty in their attempts to gain a few extra yards.
While one England World Cup winner hung his head in disappointment, another - Iain Balshaw - joined his Biarritz team-mates in wild celebrations.
Biarritz: I Balshaw, T Ngwenya, J-P Barraque, D Traille, D Haylett-Petty; J Peyrelongue, D Yachvili; Y Watremez, A Heguy, E Van Staden, J Thion, P Taele, W Lauret, B Guyot, I Harinordoquy (capt).
Replacements: B Augus (for Heguy, 69)t, S Marconnet (for Watremez, 41), F Gomez-Kodela, E Lund (for Thion, 71), T Gray (for Guyot, 50), M Bosch (for Peyrelongue, 72), C Gimenez, I Bolakoro.
Toulon: B Lapeyre, A Palisson, M Bastareaud, M Giteau, D Smith; J Wilkinson, S Tillous-Borde; E Lewis-Roberts, S Bruno, C Hayman, C Samson, K Chesney, P Gunther, S Armitage, J van Niekerk (capt).
Replacements: J-C Orioli (for Bruno, 51), L Emmanuelli, D Kubriashvili, J El Abd, G Messina, D Schofield (for Chesney, 58), F Cibray, J Suta.
Yellow cards: Hayman (46), Armitage (53)
Referee: Wayne Barnes (England)