The child was treated at the festival on Saturday August 19 after becoming “poorly” the night before, and was rushed to hospital in a critical condition.
Sadly, the child died a short time later, Staffordshire Police said on Tuesday.
Staffordshire Police said: “We were called to Camp Bestival, Weston Park, at 12.37am on Saturday following reports of a child who was taken ill.
“The child was treated at the scene and taken to hospital in a critical condition. Sadly, the child died a short time later.
“Specially-trained officers are continuing to support the child’s family and we ask that their privacy is respected at this very difficult and distressing time.
“Inquiries are ongoing to determine the circumstances of the death.”
A spokesperson for Camp Bestival said: “A child became poorly on Friday night and, after receiving immediate medical care on-site, was taken to hospital in an ambulance, where they tragically passed away.
“Our thoughts and deepest sympathies are with the family at this terrible time, and we will continue to support them in any way we can.”