Having seen the Baby Blacks grab a bonus point with four tries in the opening 36 minutes, Josh Navidi’s Welsh side salvaged some pride in the second half as they kept the score at 31-10 for 28 minutes.
But the sin-binning of prop Will Taylor allowed the New Zealanders, who made it 13 successive victories in the Under 20 event as they stayed on course for a third title in as many years, allowed the champions to end with a flourish.
Two more tries took their tally to six on the day as they raced through the 600 mark since the tournament began in Wales in 2008. New Zealand Sevens star Julian Savea got two from the right wing, full back Tom Marshall also got a brace and there were one each for  scrum half Tawera Kerr-Barlow and centre Telusa Veainu.
New Zealand skipper and outside half Tyler Bleyendaal, who was a constant threat with ball in hand, converted five of the tries and also kicked a penalty. His opposite number, Matthew Jarvis, landed a penalty in the first half and then converted a try from hooker Rhys Williams – only the fourth try the Baby Blacks have conceded in nine Pool matches at these championships.
While the New Zealanders move into the semi-finals on Thursday, Wales will have to wait until all the Pool games are played before finding out who they will meet in the 5th-8th place play-off section.
Having taken second place in Pool A, thanks to victories over Samoa and Fiji, they will be one of three runners-up who will be joined by the best third-placed team to meet in the second tier semi-finals.
Wales Under 20: Dan Fish; Kristian Phillips, Ben John, Ashley Beck, James Loxton; Matthew Jarvis, Rhys Downes; Rhodri Jones, Rhys Williams, Will Taylor, Lloyd Peers, James King, James Thomas, Josh Navidi (captain), Morgan Allen.
Replacements: Ieuan Davies, Dan Watchurst, Ed Siggery, Rhys Jenkins, Gareth Davies, Steve Shingler, Scott Williams