The event, to be held on 25 July, will celebrate the star's life with acts from the worlds of comedy, dance and music, and will also raise funds for mental health charities.
Singers Natalie Imbruglia, Louise Redknapp and Fleur East are among the first acts to be announced for the event, which will be held in the grounds of Englefield House, near Pangbourne in Berkshire.
The event committee is made up of Caroline's mother Christine and her sister Jody, as well as her close friends Dawn O'Porter, Natalie Pinkham, Anna Blue, Sarah Tyekiff and Leigh and Jill Francis.
Celebrity appearances on the day will also include Professor Green, TV presenter Dermot O'Leary, Kirsty Gallacher, Paddy McGuinness, Joel Dommett, Noel Fielding and June Sarpong.
Strictly Come Dancing stars Janette Manrara and her husband Aljaz Skorjanec will also be in attendance.
Flack, who took her own life at the age of 40 in February 2020, was crowned the winner of Strictly in 2014 alongside her professional partner Pasha Kovalev.
She grew up in Thetford, in Norfolk.
Christine Flack said: "My Caroline was never more herself or happier than at a music festival with her sister and her friends.
"Flackstock is the wonderful idea of those who knew her best and the perfect way to remember her singing, dancing and most of all laughing.
"Not only is Flackstock the most positive way to honour Carrie, but charities that she loved will benefit from the proceeds.
"A big thank you to everyone involved for all their hard work - to Natalie for the mad idea, Giles Cooper Entertainment and Englefield House who saved the day, Live Nation and to all the brilliant sponsors.
"My family are so proud that so many people who knew Carrie loved her so very much."
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Funds raised on the day will be equally split between the charities Choose Love, Mind, Samaritans and Charlie Waller Trust.
Mind's Ian O'Reilly, who is the head of community and events fundraising at the mental health charity, said: "Every donation that Mind receives through Flackstock will allow us to be there for even more people when they need us.
"This includes through services like the Mind Infoline, legal line and our online peer support community for adults, Side by Side. The money will also enable us to continue to campaign to improve services and provide information and support.
"We are honoured to be involved and we can't wait for the festival to get started."
When is Flackstock and where can I buy tickets?
Flackstock will be held on 25 July, 2022, from 4pm until 10.30pm.
Pre-sale tickets will be available from Ticketmaster on 27 April at 10am and general sale tickets will be available from 29 April at 10am.
Need help? Samaritans operates a 24-hour service available every day of the year, by calling 116 123. If you prefer to write down how you’re feeling, or if you’re worried about being overheard on the phone, you can email Samaritans at firstname.lastname@example.org