Welsh fly-half Stephen Jones scored 28 points for the home side, including one of his side’s four tries and 23 points with the boot.
Perpignan clawed their way back from 40-15 down after 50 minutes to claim a try bonus point for themselves.
The visitors scored the opening two tries through Jean-Philippe Grandclaude and Julien Candelon to give them a 12-6 lead.
Rhys Priestland crossed twice in quick succession as the Scarlets seized this Heineken Cup tie by the scruff of the neck with a four-try blitz in the space of 15 minutes either side of half-time. Jones and Regan King grabbing the other tries.
That should have paved the way for an easy win for the Welsh region who have enjoyed a love affair with Europe’s premier club competition.
Yet Perpignan began their comeback with Adrien Plante, Ovidiu Tonita and Damien Chouly all crossing to bring their side right back into game.
Perpignan were twice denied what looked certain tries before Jerome Porical missed with a last-minute penalty that would have earned a second bonus point
