The final of the Cleaning Contractors-sponsored competition was streamed live on IrishRugby.ie and went to extra-time in very wet conditions at Tullow RFC.
The 2,000-plus crowd watched Willie Wright kick Kilkenny into a 3-0 half-time lead, but Ashbourne tied things up thanks to the boot of Paul Morris.
The County Meath side, who were Division 1B champions this season, survived two yellow cards before a second Morris penalty in extra-time eventually steered them to a 6-3 victory.
The first half was a scrappy affair and some of the best chances went the way of Kilkenny who were playing with the breeze at their backs, but on countless occasions the conditions, in addition to some superb Ashbourne defending, kept them at bay.
Wright did manage to put the men from the Marble County on the scoreboard with a well-taken penalty, however he also pushed another couple of kicks wide. 3-0 was scant reward as they approached half-time.
It was in the second half though that Ashbourne's unbeaten record - they enjoyed a 14-match winning streak in this season's Leinster Junior League - was stretched to near breaking point.
Kilkenny revelled in playing into the breeze and their backs moved the ball well with Killian Everard a constant threat. The elusive winger even touched down only for the effort to be ruled out for a knock on.
With Kilkenny playing well, Ashbourne finally got themselves onto the scoreboard with a simple kick from Morris to level matters.
Although any momentum that was to be gained by Ashbourne from the score was shortlived, as both James McCaghy and Ciaran Roche were sin-binned.
It turned out to be the turning point as the Meath men held out throughout ferocious pressure which included a huge five-metre scrum. Somehow, they stood firm with full-back Dermot Colreavy covering huge ground.
The final quarter was littered with mistakes as both sides saw the finish line but neither could take that crucial extra step over it.
Into extra-time and it was Morris was emerged as the match-winning hero with his second successful penalty for Ashbourne.
Again, the valiant Kilkenny side had chances from the boot and from play to make a further impression on the scoreboard, but it was not to be.