The Lake Hāwea athlete had an outstanding Games, winning gold in the freeski halfpipe and bronze in the freeski big air.
"To be named flag-bearer is such an honour," Harrold said.
"These Games have been an amazing experience and to finish with two medals and the opportunity to carry the New Zealand flag is unreal."
New Zealand team chef de mission Marty Toomey said Harrold was chosen due to his performances and the values he displayed at the Games.
"Luke has performed outstandingly on and off the field of play," Toomey said.
"He’s an incredible athlete with a huge future ahead of him and we’re really proud to have him as our flag-bearer."
In the final day of competition, Wānaka’s Cam Melville Ives just missing out on his second medal of the Games when finishing fourth in the men’s snowboard halfpipe, following his bronze in the snowboard big air.
"The conditions were tough up there today and I didn’t quite put down the run I wanted but overall I’m really stoked with this experience and have loved being here," Melville Ives said.
Ava Beer was also in action in the women's snowboard halfpipe, finishing 14th.
The day competition rounded out the Gangwon Games.
The event was New Zealand’s most successful Winter Youth Olympic Games, the team winning seven medals — one gold, two silver and four bronze.
"This is a great group of young athletes and we’re really proud of the way they’ve represented themselves and New Zealand at these Games," Toomey said.
"The future of snow and ice sports in New Zealand is looking bright and I look forward to seeing these athletes continue to shine on the world stage in the future."
