The Blues were cheered off the field by the Arms Park crowd after a courageous defensive display in the closing stages kept Biarritz at bay.
Earlier the Blues had scored two excellent tries by man-of-the-match Gareth Williams and Jamie Robinson to twice come from behind in a display that was a fine testimony to the spirit and pride in the team.
Afterwards coach David Young paid tribute to the players' focus after a difficult time at the Arms Park
"The players are here to play rugby and I could not have asked more of them and their efforts in recent days. They have worked hard and they, more than anyone, deserve this win for themselves. But I am also delighted for the fans who really got behind us today.
"We are by no means the finished article but we will go on from this, hopefully gain more wins in Europe in the next fortnight, and then climb the Celtic League table to earn our inclusion in the Heineken Cup again next year."
Match details and report in Fixtures & Results.