A donor was found following a four-month campaign known by its Twitter hashtag #Spit4Mum.
Over 1,190 Jewish people joined the Anthony Nolan donor register in the first four weeks of the campaign as a result. The number has grown since.
Barnet now has the highest proportion of donors registered in any borough in Britain.
In July 2016 Mrs Berger received the devastating news her cancer had returned after a routine blood test and started several weeks of chemotherapy. She succumbed to the illness this weekend.
The grandmother-of-two from Kenton, north-west London, was a member of Finchley Reform Synagogue. She was treated at Hammersmith Hospital.
Jonni Berger, 37, praised “the amazing doctors and nurses who cared for her”.
Speaking about her cancer returning last summer, Mr Berger said: "She's very resilient and stoic.
“Her own personal challenge is to get through the chemo and get better as soon as possible, while our challenge as a family is to support her and to encourage as many people as possible to sign up as stem-cell donors."
At the time Ann O'Leary, head of register development at Anthony Nolan, said the charity was "extremely saddened" that Mrs Berger's cancer had returned.
