Wales U20 celebrated a fourth place finish after South Africa claimed third spot with a 43-18 victory over the Welsh at the same venue.
In Wales more than 14,000 youngsters got involved with the tournament in a WRU devised legacy programme either by watching games, attending team training sessions or meeting players and officials in their regions.
Some 400 rugby coaches from Wales benefitted from attending training sessions held by the international teams based in Wales.
The players and officials taking part have also been learning more about the host nation with the tournament guide brochure published as an entirely bilingual document in Welsh and English.
Welsh Rugby Union Group chief executive, Roger Lewis, said, "Hosting the inaugural IRB Junior World Championship has provided a wonderful opportunity for Wales and Welsh rugby.
"To welcome the rugby world once more to our nations has been a great honour for us all and we sincerely thank the International Rugby Board for granting us this privilege.
"We also have to thank the Welsh Assembly Government, UK Sport's World Class Events programme, our principal partner Invesco Perpetual and all our other commercial partners for making the tournament work so well."