The 40-year-old, known as Bowel Babe for her campaigning on bowel cancer, had initially hoped to raise £250,000 for research but the total on Friday evening surged to £4.5 million with money continuing to pour in.
Her JustGiving page reached the milestone after donations from more than 220,000 supporters, including high-profile figures such as the Duke and Duchess of Cambridge, and there was further recognition for her cause as she was made a dame.
The presenter of popular BBC podcast You, Me And The Big C disclosed earlier this week that she had moved to her parents home in Woking, Surrey, where she is receiving end-of-life care.
The dame title would normally be announced as part of the New Year honours or to mark the Queen’s birthday but can be given at other times in exceptional circumstances.
Prime Minister Boris Johnson said it was “richly deserved”.
He said: “Through her tireless campaigning and by so openly sharing her experience she has not only helped in our fight against this terrible disease, she has ensured countless others with the Big C have not felt alone. I hope this recognition from Her Majesty — backed I’m sure by the whole country — will provide some comfort to Deborah and her family at this difficult time. My thoughts are with them and Deborah should know she has the country’s love and gratitude.”
Writing on her Bowelbabe Instagram page, which she has used to document her treatment, the former deputy headteacher said she was “blown away and crying” at the honour.
She started co-presenting the Big C podcast with Lauren Mahon and Rachael Bland in 2018 and they earned praise for their frank discussions about cancer.
Ms Bland died in September of that year at the age of 40, two years after being diagnosed with breast cancer.
Her widower Steve, who joined the podcast as a host following her death, told BBC Breakfast: “Everyone is focusing on the last five days, but actually Deb has been doing this for five years, ever since she was diagnosed with incurable cancer five years ago, and since then she has just been trying to help people…
“While the last five days have been amazing — the £4 million is incredible — there are people all over the country walking around enjoying their children’s birthday parties because she has basically saved their lives.”
Ms Mahon told BBC Radio 5 Live she was “beside herself” over the news, joking that Ms James “looks like she is a dame anyway”.
London-born Ms James worked as a teacher until her diagnosis in 2016 and has two children with banker husband Sebastien.
In a typically candid Instagram post, she said: “I do not want to die — I can’t get my head around the idea that I will not see my kids’ weddings or see them grow up — that I will no longer be a part of life that I love so much.”