Ireland A, who will be going for the Triple Crown when they meet England A at Richmond in a fortnight, went ahead after 14 minutes with Henderson getting in at the corner.
Adrian Davies and Conor O'Shea then exchanged penalties before the No 8 Stuart Davies scored Wales' sole try, after a tapped penalty, to level the scores.
Ireland took a 15-8 lead just before half-time, though, with Foley driving over and Eric Elwood converting. Elwood kicked his second penalty in the 54th minute, something matched by Davies moments later.
Ireland wrapped up the match on the hour as the No 8 Barry Walsh capped an excellent performance with a fine try, Elwood adding the conversion.
Ireland clinched the Under-21 Triple Crown in convincing fashion. The home side went ahead in the first minute, when the stand-off Fergal Campion kicked a penalty, and tries by the left-wing Jan Cunningham and the prop Barry McConnell were both converted by Campion.
The Welsh prop Lee Manning then crossed for a try which the stand-off Shaun Connor converted, but another penalty goal from Campion sent Ireland in at half-time 20-7 ahead, a lead they held until four minutes from time when Connor went over.Reuse content