Born illegitimate in the suburbs of London in 1882, she was raised by her mother and aunt, then placed in an orphanage. She went to Canada where she worked as a farmhand. She returned to London at the age of nineteen. Living with her aunt, she was introduced to astrology and spiritualism.

She married and had three sons, one of whom was stillborn. Her second child died during the Spanish flu epidemic. Madge Gill then became seriously ill and lost the use of her left eye.

Upon regaining her health, she immersed herself in remarkable mediumistic work, which she would continue for the next forty years.

Madge Gill claimed to be guided by a spirit named "Myrninerest," which could be translated as "My Inner Rest." She worked at night, in very dim light, quickly, in an almost hallucinatory manner, using black or colored pencils. She also produced embroideries and writings.

Her style consists of a dizzying tangle of instinctive and proliferating ornamentation, from which female faces emerge.