Though victory was deserved with a 4-1 try-count, neither side played to expectations and it was not a good showpiece for the Division with both sides and the referee making far too many errors.
Fly half Chris Anderson, a former Neath player, opened the scoring with a penalty, but Neath hit back with a brace of tries by wing Richard Johnston, of which James Hook converted the second.
Two more Anderson penalties followed, but both he and Hook failed with attempts until Hook succeeded on the hour for a 15-9 lead. Neath skipper Gareth Morris then scored a try that Hook converted, but Cardiff replied with a dubious score from Chris Czekaj.
Another Hook penalty was followed by a corner try from Neath centre Andrew Bishop in the closing minutes.
Ebbw Vale captain Damien Hudd picked up the biggest accolade of the night at the 11th Principality Premiership Awards Evening held at Principality Stadium, after leading his side to the title for the first time.
Wales assistant coach Robin McBryde is predicting a tough battle against England on Sunday despite the fact they may not be considered to be at full strength. Players will be out to impress Eddie Jones which makes England a dangerous proposition, he says.
Wales U20 captain Tom Phillips and performance psychologist Dr Rich Neil explain why spending three days at Monmouth RFC has further strengthened the togetherness of the squad ahead of the #WorldRugbyU20s
Alongside Scarlets flanker James Davies and Cardiff Blues centre Cory Allen, three Wales Sevens core players have made the extended training squad for GB Sevens. Wales Head coach Gareth Williams tells WRU TV's Graeme Gillespie why Luke Treharne, Sam Cross and Luke Morgan earned selection in the initial training squad for Rio.
Wales Sevens head coach Gareth Williams tells WRU TV's Graeme Gillespie he has had to overcome a number of injuries before naming a competitive squad for this weekend's penultimate round of the World Series in Paris.