Grandmother Queenie Brown said the whole whanau were extremely proud of Josiah. Josiah was raised by his grandmother after losing his mum at a young age.
Mrs Brown said she was very impressed with the school during the family's three visits for the interview process.
He turned to his nana and said "Nan, I really hope I get to go here", to which she replied "I hope so too."
Josiah was "buzzing" at the sight of the senior campus located in Auckland's city centre.
Josiah had always shown a thirst for knowledge and Mrs Brown always saw great potential in her grandson.
She recalls him coming home from school to say "I love school, I get to learn heaps."
Mr Brown describes her grandson as a quiet, well-mannered kid, although he doesn't shy away from an argument with nana.
"He's a champion boy."
"Even when he's on the internet I find him watching educational videos."
Josiah eagerly awaited his fate in the mail.
"He was pretty emotional, all the family was there to give him hugs and pat him on the back."
Josiah has a little sister who he is very protective of and the pair have a "very strong bond".
Not content with dominating in the classroom, Josiah is also a star on the sports field.
He recently placed second in his schools cross country and is a keen basketballer.
In February, Josiah will start his secondary school education at Te Haerenga, Dilworth's rural campus for Year 9 students.
The school has a long and proud history of educating talented young men from families and communities with very limited means.
Esteemed alumni include a former governor-general and prime minister.
"He will succeed, I'm just worried that he'll get homesick," Mrs Brown said.
All students attend on full boarding scholarships without parents and families having to pay.
"They told me that I would be giving them a boy and getting back a man," Mrs Brown said.
Josiah, whose favourite subjects are Maths and PE will be leaving for school on February 2.