The parents of cerebral palsy sufferer Scarlett Hewitt, aged eight, of New Addington, last week appealed for help in their battle to raise £65,000.
The money would be used to fund life-changing surgery at a leading American children's hospital.
After friends of her Eagles supporting father, John, posted the Advertiser's story on Crystal Palace fans' forum the BBS, donations shot up.
But what Mr Hewitt and his wife Lisa did not expect was the response from supporters of Palace's rivals Brighton and Hove Albion.
Mr Hewitt said: "It's quite amazing really, it's great that both sets of fans can get together to help a good cause.
One Palace fan said he would wear a Brighton shirt to the last home game of the season if Brighton fans raised more than £500.
Well they've already smashed that. We're really overwhelmed."
Tree of Hope offers hope to the families of sick and disabled children in the UK who need specialist medical surgery, treatment and therapy in order to free them from suffering, giving a better quality to their young lives.