While Anderson carded back-to-back wins, men's slopestyle winner Sebastien Toutant, of Canada, was celebrating his debut win in a major international snowboarding event.
The Montreal boarder dominated the men's event, winning the title with a standout aerial performance from a strong field of seasoned international riders.
Anderson had qualified in second place for the finals behind New Zealand's leading snowboarder, Shelly Gotlieb.
However, a strong second run from the two-time Winter X Games slopestyle champion pushed Gotlieb into second spot, before a final run from Janna Weatherby (US) caused further frustration for the New Zealander.
Gotlieb tried to step up with a pair of technically demanding airs in her final run, but misjudged her landing and had to settle for third place.
She was upbeat about her result, saying she was happy with the improvement from her fourth placing last year.
"I was trying to get a good clean run down before trying any harder tricks. In competitions you have to ride smart and solid," Gotlieb said.
"I achieved that with my first and second runs, but didn't quite stick things as I wanted with my third. I got caught up with my landings a little."
Anderson said she was mellow heading into her final runs, despite qualifying behind Gotlieb.
"I try to mix my runs up in the finals and try things a little different," she said.
Anderson will return to try to defend her 2008 Burton Open halfpipe title today, though she said she had not practised this week.
Toutant said he was "so stoked" to win his first major event.
He will take his place alongside a men's halfpipe field of 42 riders today.
Wanaka snowboarder Stef Zeestraten was the only New Zealander to qualify for the men's slopestyle finals, producing a strong third run to finish sixth.
Treble Cone extreme skier Alex Llynden was the standout performer on the opening day of the New Zealand Freeski Open big mountain competition at the Remarkables on Thursday.
Llynden, a freeski instructor at Treble Cone, was the top qualifier in the mountain event.
Big mountain freeskiing is not for the faint-hearted.
Skiers take some of the steepest and most extreme lines down the mountain, often throwing themselves off cliffs and rock faces.
Wanaka's Sam Lee (17) skied some tight lines to qualify in fourth place behind Llynden, Switzerland's Geremie Heitz and Neil Willman, of Temple Basin, Canterbury.
Italian Arianna Tricomi was the top female qualifier, followed by Sarah Gillespie, of Maungawera near Wanaka, in second.
Wanaka's Nicola Campbell, a New Zealand representative at the 2006 Winter Olympics in Turin, qualified in third place.
She switched skiing disciplines to big mountain events two years ago.
Fourteen men and four women from the qualifications have progressed to the final round and will join a field of eight pre-qualified men four women in the finals, scheduled for the Alta Chutes at the Remarkables today.
