The Arms Park side established an early 10pts to nil lead but the home side battled back to lead 20pts to 10 midway through the second half. However with the introduction of influential fly half Nick Macleod, the Arms Park youngsters levelled with two tries scored in quick succession and Macleod added a late penalty and drop goal to secure both the win and title.
Prop Darren Ryan, wing Andrew Henry and centre Owain Ashman scored tries for the visitors while fly half Chris Anderson landed an early penalty and conversion before the dramatic intervention of Macleod.
Wing Elia Pellegrotti and scrum half Alun Lake replied with tries for the Brewery Field side with fullback Lloyd Warner adding a brace of conversions and penalties.
Llanelli U'21s maintained their pursuit of the runners up position with a 26pts to 21 success away to Ebbw Vale.
Number eight Aled Gravell was in superb form for the young Scarlets scoring two tries, one of which was described as the seasons best. Flanker Steve Thomas was also in fine form while wing Llyr Davies and centre Mark Sweeney crossed for further tries for the visitors.
Fly half Caerlon Thomas secured the victory with a hat trick of conversions. Centre Gareth Roberts and Gareth Green replied with tries for the home side and Ross Watts added a further try and three conversions.
Cardiff v Neath
U21 Cup Final
This Wednesday 24th April, 7.15pm at Bridgend RFC
Whenever Bedlinog tackle Penallta a massive fixure is guaranteed but this Sunday there will be even more emphasis placed on the two rivals when they contest the SSE Swalec Plate final at Principality Stadium.
Ahead of their SSE SWALEC Bowl Final clash with Taffs Well at Principality Stadium on Sunday, Burry Port share their #FABXV nomination with WRUTV in the search for Welsh rugby's greatest volunteers. Everyone can get involved by sending nominations via twitter to @WRU_Community using the hashtag #FABXV
Cardiff Blues prop Gethin Jenkins and Ospreys centre Ben John look ahead to the first game at Principality Stadium in Saturday's double header which is promising to be a special occasion for all Welsh fans.
Carmarthen Quins Director of Rugby Ian Jones and committee member Jeff Thomas along with Llandovery chairman Handel Davies look ahead to Sunday's SSE SWALEC Cup showdown where both teams are out to prove 'West is best'
SWALEC ambassador Shane WIlliams is looking forward to Sunday's Finals Day where the Cup, Bowl and Plate offers a great opportunity for players and teams to experience the magic of playing at Principality Stadium
Carmarthen Quins coach Richard Kelly believes it is an exciting time to be part of the Scarlets region as his side take on local rivals Llandovery in the SSE Swalec Cup final on Sunday, as WRU TV's Graeme Gillespie discovers