The Irish Under-20s missed out on the title on scoring difference, as France's 43-10 final weekend defeat of Italy saw them finish top of the table - albeit level on eight points with Allen Clarke's men.
Winning their fourth game of the tournament, Ireland bounced back from their loss last week to Scotland as they dug deep during a scoreless second half to to finish as 9-6 winners over Wales.
Speaking to IrishRugby.ie after the Llanelli encounter, team captain Peter O'Mahony said: "To be fair to Wales, they're a very physical side. We talked about that before we came here and we knew exactly what they were going to give us - we expected nothing less.
"We were happy enough to grind that one out, to be honest.
"Credit to the Welsh boys, they're a super side. But even more credit to my boys, they were outstanding.
"I thought we matched them and were better up front. (I'm) proud as punch of the lads."
Three penalty goals from out-half Andrew Burke, the third coming in the 23rd minute, had the visitors ahead and O'Mahony had praise for his fellow Munster Academy member and the Irish management team afterwards.
"Credit to Andy, he stood up in the first 25 minutes. As I said, we're happy enough to take 9-6...3-0 would have done me fine."
He added: "(The management team, led by Allen Clarke and manager Phil Orr) are super. I couldn't talk higher of the boys.
"They were with us through everything and they gave us as much support as we needed. They were always there for us, so all credit to them."
The Six Nations is over for another year and June's IRB Junior World Championship, which is being staged in Japan, is looming large on the horizon.
Some tough fixtures lay ahead for O'Mahony and the squad - not least their pool opener against Argentina in Nagoya on Friday, June 5 - and it will be all about getting the preparations right in the coming weeks.
"It was disappointing (not to win the title). Our goal at the start of the Six Nations was to win the Grand Slam.
"It wasn't to be but we'll take all the positives out of this Six Nations and we'll head towards the Junior World Championship in Japan.
"The next eight weeks are crucial for us development-wise for that tournament.
"Obviously we'll go back playing AIB League rugby, work on our fitness and bulk and that kind of stuff.
"We're all looking forward to the World Championship now as a group and we'll just tip away."