A statement from her representative said: “It is with immeasurable sadness that Nikki Grahame passed away in the early hours of Friday 9th April 2021.
“Please respect the privacy of Nikki’s friends and family at this tragic and difficult time.”
Grahame, originally from Northwood in London, appeared on the seventh series of the reality TV show in 2006, and despite finishing fifth became one of its most recognisable characters.
She subsequently secured her own show, Princess Nikki, won a National Television Award and published two books, the autobiographies Dying To Be Thin and Fragile.
Grahame had recently received treatment for an eating disorder at a specialist clinic following a fundraising campaign organised by friends and fans.
A statement on the Gofundme.com page said: “It is with great sadness, we have to let you know that our dear friend Nikki passed away in the early hours of Friday 9th April.
“It breaks our hearts to know that someone who is so precious was taken from us at such a young age. Nikki not only touched the lives of millions of people, but also her friends and family who will miss her immensely.
“We would like to request privacy at this difficult time, while Nikki’s friends and family process the sad news.
“Full details will be released as and when we know them.”
Prior to finding fame on Big Brother, Grahame, then an aspiring actress, appeared as an extra in the BBC soap opera EastEnders and played a footballer’s wife in Sky One’s Dream Team.