Speaking to the Herald, O'Neill's mother said the win was a surprise for both her and her daughter.
"I'm very happy for her and quite surprised. This morning Hannah said 'oh there's no way'."
But there was no time to bask in her victory as O'Neill performed in the award gala just moments after her win.
This year marks O'Neill's fifth season with the Opera National de Paris. She was awarded a lifetime contract in 2013.
She started dancing at 3, having inherited her athleticism from her father, who once played rugby professionally in Japan.
Born in Japan to a Kiwi father and Japanese mother, the ballerina was 8 when her family moved to New Zealand. She has two younger brothers, Shimon and Ben.
O'Neill went to Parnell District School and Epsom Girls' Grammar, and also attended the Mt Eden Ballet Academy - which she credits for playing "a big part in my development as a young dancer".
From there she went to the Australian Ballet School in Melbourne and then to France.
She got a contract with the Opera just before turning 21.
Along the way, she won a string of overseas scholarships and ballet competition titles.
In 2013, she was among the finalists for the Herald's New Zealander of the Year title.
O'Neill has some advice for other Kiwis wanting to follow in her footsteps - she says they need "motivation", "work ethic" and "belief in yourself".
The desire to do it also has to come from "your heart".
