Born in 1803, Eliza Flower was the elder of two sisters born to Benjamin Flower and Eliza Gould. Their early years were spent in a household of liberal political opinion and religious observance; Flower spent time in prison for his beliefs, and Gould was known for her philanthropy and work with prisoners. After the death of Flower in 1829, the preacher and political reformer William Fox became guardian to the sisters, and Eliza would remain living with him until her death from tuberculosis at the age of 43, in December 1846.

From the age of four, Eliza showed a talent for music. Harriet Martineau, in Five Years of Youth, based the character Anna on Eliza:

He was delighted with Mary's singing, which was very unlike what he had heard from any other young lady since he had been in England. She had been well taught; but she had that natural taste for music – the ear and the soul for it – without which no teaching is of any avail. She sang much and often, not because she had any particular aim at being very accomplished, but because she loved it; or, as she said, because she could not help it. She sang to Nurse Rickham's children; she sang as she went up and down stairs; she sang when she was glad, and when she was sorry; when her papa was at home, because he liked it; when he was out, because he could not be disturbed by it. In the woods, at noon-day, she sang like a bird, that a bird might answer her; and if she woke in the dark night, the feeling of solemn music came over her, with which she dared not break the silence. Every thing suggested music to her. Every piece of poetry which she understood and liked, formed itself into melody in her mind, without an effort: when a gleam of sunshine burst out, she gave voice to it; and long before she had heard any cathedral service, the chanting of the Psalms was familiar to her by anticipation.

Eliza went on to compose songs and hymns, the most famous of which is still Nearer My God To Thee, written to a poem by her sister Sarah. A review in The Church of England Quarterly Review showered praise on Eliza’s sacred music:

It is with great pleasure that we preface these remarks with the title of a work lately produced by an English lady, for it requires no great exercise of critical skill to point to Purcell and Mendelssohn as the objects of Miss Flower’s ambition, and her great success is an ample proof of the propriety of her choice. We do not hesitate to pronounce this first part of “Adoration, Aspiration, and Belief,” to exhibit genius of the highest order.

Eliza was a close friend of figures such as John Stuart Mill and Robert Browning.