Alice New, six, made the decision to have her hair, which stretched down to her legs, cut and donated to the Little Princess Trust, which provides real hair wigs to children who lose their hair through medical treatment.
The family, from Donnington, were proud that she came up with the idea off her own back.
Her grandmother Denise Birkett, 62, said: "Alice is quite a caring child. Her mum is a trainee midwife, she is like that.
"She has just come up with the idea herself. She said 'nanny, can I have my hair cut to make some wigs?'
"We prepared her because we knew how much her hair meant to her – we call her Rapunzel."
Sponsorships were taken and £570 was raised for the charity, which also funds cancer research.
On the day itself, Jack Charles from Donnington-based U2 Hair Salon did the deed. The company even donated £30 to make the total up to £600.
"They were brilliant," said Denise.
"Alice loves [the new style], she has it in a bob. She said it's beautiful.
"She also said 'I didn't have to brush it this morning'!"
Learn more about the trust at littleprincesses.org.uk/.