Henrietta grew up in an isolated part of New Forest in Hampshire, England where she learnt how to ride a horse and about animals. After living in many other places she moved she later moved to Southampton in 1980 with her husband Paul Carter who was a photographer and together they have had 3 children named Jack, Rose and Polly.

She started her writing career when she was 40 and in 13 years until her death in 1999 she wrote 25 books for toddlers to teenagers. Before her writing career she had a variety of jobs including as a nanny, in shops, hotels and offices and for a charity helping elderly people in South London. She did train as a community and youth worker at Goldsmiths College from 1970-1972 but didn't enjoy it. The first novel she wrote was called Royal Blunder which started her writing career well. Other novels she has written include Fire, Bed and Bone, The Fated Sky.

Henrietta was diagnosed with breast cancer in December 1997. During the following years she had three operations and chemotherapy, but her cancer turned out to be very vigorous and could not be treated effectively. She later died at home aged 53 in Southampton on April 23, 1999.

After her death, Julia Eccleshare and Anne Marley decided to form 2 annual awards: Branford Boase Award (for first time writers) and the Henrietta Branford Writing Competition (for children) in memory of herself and Wendy Boase. Henrietta had originally thought of the idea before she had died and so Julia and Anne made sure that her ideas were used.