Geoff Griffiths’ side edged a tight encounter by a single point, eventually prevailing 20-19.
They could have lost the match in the 84th minute though, Rhydyfelin’s Josh James lining up a late, late penalty which would have seen them crowned Plate champions.
Luckily for Heol y Cyw, the kick went wide and the men in blue hung on to clinch the silverware.
Head coach Griffiths said: “The match was a heart-stopper. There wasn’t much in it but it was important we came back and scored straight away after their first try.
“The whole experience has been massive for the club. I’ve been coaching the side for four or five years and we’ve come up from division four to one and now to win this is incredible.
“The crowd was great today. The Millennium Stadium is the best in the world and to come here and play and be part of a winning side was enough to bring a tear to my eye!”
A brace of tries from Chris Howe proved to be the difference against Rhydyfelin, the centre crossing twice in the first half as his side led 17-11 at the break. The left boot of fly half Mike Huckridge had done the rest.
Another three points from Huckridge was the only reply for Heol y Cyw after half time but it proved to be just enough.
Rhydyfelin’s Gavin Close had scored two tries of his own to set up a nail biting finish, one in which James could still have won it.
It was not to be for Rhydyfelin though as Heol y Cyw celebrated.
“It has been an amazing, once in a lifetime opportunity,” said Heol y Cyw captain Adam O’Driscoll.
“We always had the belief we could win and to come back after they took the lead shows how we work hard for each other.
“Heol y Cyw is only a small village so hopefully this will encourage more people to come along to the club having watched us on television and here at the stadium.”
