SCARLETS No 10 Aled Thomas broke Edinburgh hearts with a 78th-minute penalty, following a harsh offside call by the touch judge after the Scots had come from behind to lead.
Replacement Alex Toolis went over in the corner, Greig Tonks slotted the conversion to put his side ahead, but the comeback was in vain. Edinburgh kept the ball in hand and stretched the Scarlets in the first half, but despite their pressure they did not make the most of their opportunities.
A stray Edinburgh hand touched a kick through which allowed the Scarlets players who would have been offside to reclaim the loose ball. They spread it wide where the Scots defence made it too easy for Morgan Allen to bullock his way over from 30 metres out.
Steven Shingler added the conversion and a penalty before he went off injured, but replacement Thomas notched a penalty with his first kick as Scarlets took a 10-point lead.
Edinburgh scrum-half Nathan Fowles landed his first penalty but hit the post with his second just before half-time.
Fowles and Thomas exchanged penalties early in the second half, before Edinburgh forced their way back into the game with Cornell Du Preez barging over from close range. Toolis added a second try, but they had to be content with a losing bonus point.