"I feel really proud," she said. "I'm from Northland, and I'm from Dargaville - it just goes to show that it can be achieved if you set your mind to it."
Husband Ross, also a swimming official, is on Fina's open water swimming list.
Swimming New Zealand life member Ross Bragg, a former international swimming referee, said selectors would have recommended Gillespie to the Fina technical committee on the standard and quality of her work.
He said officiating at a big international event was the same job, but also quite different in subtle ways.
"It's a matter of fitting in and working out what they want, how they want you to perform.
"The thrill of being there is just magic - and you're working in facilities that are like a dream, compared to some here [in New Zealand]," he said.
The Fina World Championships will be held in Budapest from 14 to 30 July, at the new Dagaly Swimming Complex; and the World Para Swimming Championships in Mexico City from 30 September to 6 October, at the Francisco Marquez Olympic Swimming Pool.
These two trips will be the first paid ones in her 14 years of officiating - everything else Gillespie has done has been self-funded, including a five-day para swimming course in Singapore last year, and officiating at the Oceania Swimming Championships last year in Fiji.
"Everyone assumes you get paid [for what you do as an official]," she said.
"People ask me: 'Do you have children swimming?' and when I say no, they say, 'Oh, does Swimming Northland pay you?'
"They can't believe that someone does this as a volunteer. But everyone has a hobby, and this is mine."
Gillespie is passionate about the sport of swimming, and enjoys the countrywide network and support system of fellow swimming officials, describing them as more like a family.
It's a role Gillespie stepped into reluctantly 14 years ago when daughter Taryn, now 23, was a swimmer. She began timekeeping at Northland's Rising Stars competition, an event for young swimmers where many parents find themselves taking on an official role for the first time.
In subsequent years, she avoided being roped into more senior positions but was eventually talked into becoming an inspector of turns (IOT).
Rising Stars, once again short of officials, prompted her to step up to judge of stroke and then referee, and she began applying as an IOT at national meets.
From there she was persuaded to referee at national competitions, the first a New Zealand juniors meet in Hamilton.
"I always swore I'd never be a referee. I was terrified. It was scary, but I also knew I had people around to support me".
Gillespie took the advice of a fellow official to never turn down a job, to just do it . "And I'm thankful for that - sometimes."
That mindset, of always stepping out of her comfort zone, has now launched the Dargaville woman into her latest and biggest adventure in the world of swimming officialdom.
"I'm going into the unknown - it's going to be an eye-opener."