Having already bagged the Division One East Central title, Ystrad made sure with a 75-36 aggregate victory over One East champions and WRU National Plate winners Brynmawr.
The first leg at Gelligaled Park resulted in a 47-31 win for the hosts and, with that 16-point advantage heading into the second leg, they finished the job in style, running out 28-5 victors.
Promotion for Ystrad comes after five consecutive seasons finishing as league runners-up.
“We’re over the moon,” said delighted club secretary Alan Sinclair. “It’s been a long-time coming, it was great to win the league but winning at Brynmawr was really the icing on the cake. It’s tremendous.
“The boys were just absolutely awesome and to go to Brynmawr and win in the style that we did was exceptional.
“I couldn’t be more proud for the boys, the coaching staff, all the backroom staff, everybody, for the hard work – over the last six years really.”
As well as the play-off with Brynmawr, Sinclair also picked out the 29-18 win at rivals Glamorgan Wanderers on April 14 that put them on the brink of the title.
He added: “With regards to the league, it was the win at the Wanderers.
“To beat them having had two men sent off in the first half and the way we dug in and turned the result around [from 18-5 down] was absolutely exceptional.”
