Her son, Joshua, and daughter-in-law, Jasmine confirmed that the former actress had suffered multiple seizures in the lead-up to her death. The devastated couple left a simple message of the news via a Facebook page they had set up to inform fans of updates regarding Nickerson’s health.
"She's gone," is all the post said.
An earlier post by the couple gave more details of her deteriorating condition.
"They just took off all the equipment. None of it was helping, but making her only more uncomfortable," they wrote.
"We're telling her it's okay to let go."
Nickerson’s son also set up at GoFundMe page, asking fans to donate to help cover his mother’s medical costs.
"We need help. We cannot afford to pay for death expenses. Although she had the fame and notoriety, there is no inheritance. No life insurance. No end of life nest egg," he wrote.
It is understood Nickerson suffered a stroke a year ago and had since entered a “coma-like state.”
"We are heartbroken and reliving a grief we've lived every single day since she had the stroke over a year ago."
Nickerson rose to fame in her teens after landing the role of bubble-gum-chewing Violet in the first movie version of Roald Dahl’s iconic children’s book, opposite Gene Wilder’s Willy Wonka.
She was also known for her appearances on Sesame Street companion series The Electric Company and on Dark Shadows, before retiring from acting aged 21.
In a statement to Fox News, actress Julie Dawn Cole, who played the spoilt Veruca Salt said: "It is dreadfully sad.
"Denise has been like a sister to me and we were very close. She had a massive stroke last July and never really recovered. Paris [Themmen] (who played Mike Teevee) and I went to visit her in September. It was a very sad visit as she couldn't verbally communicate. But we sang songs - 'Willy Wonka' of course! And that made her smile and laugh."