Brave twin Paris Leigh Boycott, 12, stumped sister Autumn and her family after telling them she wanted to undergo the head shave just before Christmas.
The determined youngster, from Dewsbury Road, Wakefield, took on the challenge after seeing family members battle cancer.
Her long, blonde hair has now been donated to the Little Princess Trust charity, which makes wigs for children suffering from hair loss.
Mum Michelle Boycott said: “Everyone is so proud of Paris, she is so brave.
“To do something like this at just 12, because their appearance is important at that age.
“She has always been like this, since a young age Paris has always given her pocket money to homeless people, or brought them a drink.
“She dropped this decision on me just before Christmas because she is more aware of cancer now with starting high school and she has watched videos and seen girls with alopecia.
“That’s why she wanted to shave her hair, instead of just cutting a bit off, so she can make a full wig.
That’s what she is like, she’s that kind of child.”
The Cathedral Academy pupil had the scissor treatment done by her aunt, Donna Allen, at home.
Her decision comes after losing her great-grandmother following a cancer diagnosis, and her uncle and former cricketer Geoffrey also battled with the disease.
Miss Boycott, a teaching assistant at Flanshaw Junior and Infants School, Wakefield, added: “Paris is beautiful inside and out, she is a stunner and very popular in school.
“Now she’s more aware she is always asking about cancer and what you have to look for with breast cancer.
“She knows her uncle Geoff has had cancer and will always be in remission and her great grandma died of cancer so she didn’t get to meet her.”
Geoffrey Boycott is a former Yorkshire and England cricketer, who is originally from Fitzwilliam, near Wakefield.
The Little Princess Trust is a charity that provides real-hair wigs for children suffering from hair loss. The organisation relies on donations of hair in order to provide wigs to young people in need. People can also help fundraise for the charity and apply for a fundraising pack. For more information about the charity, or to donate, visit www.littleprincesses.org.uk/