The two-year-old tot was able to come out of hospital and spend the day with family and friends at the event, held at Moorthorpe Recreational Club.
More than £2,300 was raised including a £500 cheque from South Kirkby Town Council and money raised by ET Martial Arts Academy of Seven Golden Dragons.
Joanne Speight, a long-term friend of the Michalowski family, helped to organise the fun day.
She said: “It was a great day.
“What has happened to JJ has really brought the community together. The SESKU community spirit is immense and we’ve nearly reached our target.
“The family is absolutely overwhelmed by the support and generosity they have received. It has restored their faith in people.”
The fun day included live music, chocolate making, a fire eater, a stilt walker, donkeys, a fairground and stalls.
Katy Michalowska, JJ’s mum, said: “It was an absolutely fantastic day. It’s amazing how much money has been raised in two months.
“We’re currently at Stoke Mandeville Hospital, where JJ is receiving brilliant care. He’s even had a go in a wheelchair which has brought a massive smile to his face.