Claire Jones, 36, finished fourth in the women’s 40-and-under category and fifth woman overall after continually lowering her personal best time.
The challenge comprises five ironman-type tasks including climbing a six-storey tower carrying a 19kg hose, and dragging a life-sized dummy for 30.5m.
The gut-busting tasks are performed while wearing full bunker gear and breathing apparatus.
Jones qualified for the Stuart, Florida event by breaking 3min in the open women’s section of the National Firefighter Challenge in Wellington in May.
She recorded 2min 57sec, easily beating her personal-best time of 3min 31sec.
In her first run in the US, she notched 2min 52sec, which she broke again with 2min 44sec in her second run to qualify her for last weekend’s finals.
Jones then smashed that time again with an amazing 2min 27sec in the event finals despite 30°C temperature.
Her partner Holly Alldred, who joined her on the trip to Florida, said she was very grateful to her sponsors and all those who made her trip possible.
"All the hard work, early morning gym sessions and work with her team in Queenstown has paid off.
"A great time was had by all, and Claire is already planning for next year," Alldred said.
The New Zealand women’s team finished fourth in the relay category.
By Philip Chandler