Lilly, an eight-year-old pupil at The Priory Primary School in Wednesbury, is set to join about 30 other girls at a special charity event which will see their ponytails lopped and their hair restyled by professional hairdressers.
Tina Tonks, Lilly's 34-year-old mother, said: "She decided it would be a good idea to help children with cancer.
"Her hair hangs down beyond her waist and she has previously only had it trimmed.
"She decided to raise money for charity through the Matts Mission Children's Donation Charity which organises the special Princess Days to help raise vital funds."
Tina, who also has a four-year-old daughter, Isabelle, said: "We are waiting to hear when and where the event will take place.
"My 54-year-old mother, also named Tina Tonks, was diagnosed with leukaemia six years ago and so I think Lilly really wanted to help children who have had a cancer or who are going through chemotherapy.
"So far friends and family have said they will donate and we are hoping many more ill see the Facebook page for the donations charity or look at my online profile. page."