The charity was set up after the death of 14-year-old Ellie Othick-Bowmaker from two brain tumours last year.
It provides practical assistance to families of children with brain tumours and other cancers, and supports research projects.
Lady Ayckbourn, wife of playwright Sir Alan, said: “I had read about the work of Ellie’s Fund in the newspapers and it’s wonderful to hear about how much they have already achieved.
“I don’t claim to have access to all of the great and the good in Yorkshire but if I can help by attracting more attention to the charity in my new role as patron, then I am happy to do so.”
Ellie was just 11 when she was diagnosed with a grade 4 glioblastoma, a brain tumour, in March 2007.
She defied doctors’ expectations and underwent a seven-and-a-half hour operation, six weeks of radiotherapy and 26 months of chemotherapy.
Ellie was diagnosed with a second tumour in 2009 but by that point had raised well over £10,000 for the charities that had helped her through the illness. She died in February 2010, three years after she first became ill.
Ellie’s mother, Heather Othick, said: “It’s great to have Heather on board and I’m sure that she will help raise the profile of Ellie’s Fund in the region.
“We’re already offering help and support to young people in Kirkbymoorside, York, Doncaster, Sheffield and Harrogate as well as children and teenagers in Scarborough.
“The help and support we provide really does make a difference to people’s lives and with Heather’s involvement I’m sure our charity will grow and we will be able to help even more people.”