Stunning tries from Owen Lane and Josh Adams were not enough as Cardiff Blues paid the price for mistakes in a fiercely fought Welsh derby.
Cardiff Blues academy graduate Leigh Halfpenny got the scoring underway with a pair of penalties against his former side at a sold-out Cardiff Arms Park.
The hosts bounced back in fashion thanks to a superb finish from Welsh international, Lane, before Gareth Davies replied for the visitors with a trademark interception, as they took a healthy nine-point lead into the interval.
Adams crossed for his side's second of the evening, but a late Tovey miss from distance saw the visitors run scrape their way to a win, having failed to add points after the interval.
John Mulvihill's side return to European action next week as they travel to Leicester for a crucial Challenge Cup encounter.
Cardiff Blues got off to an electric start in the capital with Jarrod Evans slicing the Scarlets in half from just the second phase. He drew Leigh Halfpenny before releasing Josh Adams but the in-form wing was caught by Ryan Conbeer.
Moments later Evans had the opportunity to open the scoring, but his effort sailed right of the uprights.
A pair of penalties offered the Scarlets their opening into the game as former Arms Park favourite Leigh Halfpenny booted the scoreboard into action for a 3-0 lead.
A further fortuitous penalty, which left the capacity crowd bemused, saw the Wales full-back double the visitors’ advantage.
The Blues continued to play with pace and intensity with Evans and Ben Thomas combining to good effect. A series of sweeping attacks saw Wales’ Capital Region work their way to the Scarlets try-line only for the visitors to cynically infringe.
They were fortunate not to see yellow and the Blues went to the corner, only to lose the lineout as the opportunity was lost.
Cardiff Blues finally claimed their first points on 25 minutes as they took the lead for the first time. There were two moments of brilliance as Hallam Amos bamboozled the Scarlets defence after collecting loose ball and then release Lane with an offload out the back.
Lane then tore down the right before hacking ahead and winning the race to claim a stunning try. Evans converted to take a slender lead, but it lasted just four minutes as the Scarlets dealt a sucker-punch.
The Blues were continuing to play an open and expensive game but it backfired as Gareth Davies picked off an Evans pass to claim a 60-metre interception try.
Halfpenny added the extras to restore the West Walian’s six-point advantage, but the Blues continued to cause the visitors problems.
On numerous occasions they broke the Scarlets defence but they were unable to convert as first Ken Owens and Josh Macloed combined to claim a vital turnover and then mistakes crept in to halt any progress.
To make matters worse, the Blues were harshly penalised on the stroke of half-time and Halfpenny stepped up to make it 16-7 to the visitors.
The Blues lost Evans at the break and his replacement, Jason Tovey, was off target with a penalty on 48 minutes.
The encounter remained in the balance with the Scarlets enjoying the better of the territory but Cardiff Blues defending with venom.
They soaked up sustained pressure and as the clock passed the hour mark they stuck for another stunning try.
Hallam Amos owned the skies as he claimed a towering up and under despite heavy traffic and when the ball was spread left Rey Lee-Lo and Adams combined emphatically.
The Samoan centre eased onto the outside of Steff Hughes before putting Adams in space. He then returned the ball to Lee-Lo , who drew Halfpenny before once again passing to Adams who then stepped inside the Scarlets cover defence to finish.
Tovey added the extras to cut the Scarlets lead to just two points, but he was unable to land a long-range effort to give his side the lead on 70 minutes after Josh Turnbull smashed Ryan Conbeer into a new stratsosphere.