She was born at Kent Terrace, London, on 27 July 1831, was only daughter and youngest of three children of John Taylor, wholesale druggist of Mark Lane, and his wife Harriet, daughter of Thomas Hardy of Birksgate, near Kirkburton, Yorkshire, where the family had been lords of the manor for centuries. Taylor, a man of education, inspired his daughter with a lifelong love for history and strong filial affection from an early age. Helen's education was pursued desultorily and privately. She was the constant companion of her mother, who, owing to poor health, was continually travelling. Mrs. Taylor's letters to her daughter, shortly to be published, testify to deep sympathy between the two.
The father died in July 1849, and in April 1851 Helen's mother married John Stuart Mill.
Her mother, Harriet Taylor Mill, wanted Helen to be free to do "what she hoped all women would one day have the liberty to do: to work at a job of her own choosing. The "experiments in living" that Harriet and John Stuart Mill encouraged in On Liberty began with her own daughter, Helen.
Helen followed her dream of becoming an actress and went to work at Sunderland in 1856 and worked as an actress for two years.
Mrs. Mill died on 3 November 1858 at the Hotel de l'Europe, Avignon, when on the way with her husband to the south of France. In order to be near his wife's grave Mill bought a house at Avignon, which subsequently passed to Miss Taylor. Miss Taylor now devoted herself entirely to Mill, and became his 'chief comfort.' She not only took entire charge of practical matters and of his heavy correspondence, answering many of his letters herself, but also may have co-operated in his literary work, especially in The Subjection of Women (1869), much of which might have been suggested by her mother. Mill used to say of all his later work that it was the result not of one intelligence, but of three, of himself, his wife, and his step-daughter. Mill died in 1873.
Miss Taylor, who had edited in 1872, with a biographical notice, the miscellaneous and posthumous works of H. T. Buckle, a devoted adherent of Mill's school of thought, edited in 1873 Mill's Autobiography; and in 1874 she issued, with an introduction, his essays, Nature, The Utility of Religion, Theism.
Mill's death left Miss Taylor free to enter public life and so further the social and political reforms in which her step-father had stirred her interest. Possessed of ample means, which she generously employed in public causes, she made her home in London, while spending her holidays at the house at Avignon which Mill left her. On all subjects her opinions were radical. Her principles were at once democratic and strongly individualist, but she favoured what she deemed practicable in the socialist programme. A fine speaker in public, she fought hard for the redress of poverty and injustice.
Mill had refused, in 1870, through lack of time, the invitation of the Southwark Radical Association to become its candidate for the newly established London School Board. In 1876, Miss Taylor accepted a like request, and was returned at the head of the poll after a fierce conflict. Although a section of liberals opposed her on account of her advanced opinions, her eloquence and magnetic personality won the support of all shades of religious and political faith. She was again returned at the head of the poll both in 1879 and 1882. She retired in 1884 owing to ill-health, but during her nine years' service she scarcely missed a meeting.
Her educational programme included the abolition of school fees, the provision of food and shoes and stockings to necessitous children, the abolition of corporal punishment, smaller classes, and a larger expenditure on all things essential to the development of the child and the health of the teacher. While she was a member of the board, she provided at her own expense, through the teachers and small local committees, a midday meal and a pair of serviceable boots to necessitous children in Southwark. She was a prominent member of the endowment committee of the board, and was successful in inducing the charity commissioners to restore some educational endowments to their original purposes.
A zealous advocate of the reform of the industrial schools, she brought to public notice in 1882 certain scandals imputed to St. Paul's Industrial School. The home secretary instituted an inquiry, and the school was ordered to be closed. In June 1882, Thomas Scrutton, a member of the school board and chairman of its industrial schools sub-committee, brought an action for libel against Miss Taylor. Sir Henry Hawkins was the judge, Sir Edward George Clarke was Miss Taylor's counsel, Sir Charles Russell, afterwards Lord Russell of Killowen, was for the plaintiff. On the fourth day, 30 June, Miss Taylor's case broke down on the plea of justification, and Miss Taylor paid the plaintiff £l000. by consent. The judge acknowledged Miss Taylor's public spirit and exonerated her from any personal malice. Her action brought about a drastic reform of the London industrial schools.
At the same time, Miss Taylor threw herself with equal energy into political agitation. She was active in opposition to the Irish coercion policy of the liberal government of 1880–5, and was one of the most energetic supporters of the English branch of the Irish Ladies' Land League, frequently presiding at its meetings both in England and Ireland. Anna Parnell, Irish nationalist and younger sister of Irish Nationalist leader, Charles Stewart Parnell, was often her guest. The causes of land nationalisation and the taxation of land values powerfully appealed to her. She was a leading member of the Land Reform Union, and of the League for Taxing Land Values, addressing in their behalf large audiences, chiefly of working men, both in England and Ireland. Her enthusiasm for land nationalisation brought her the acquaintance of Henry George, the American promoter of the policy. He stayed at her house in South Kensington in 1882. In his opinion she was 'one of the most intelligent women I ever met, if not the most intelligent'.
In 1881, Miss Helen Taylor's faith in the practicability of certain socialist proposals led her to take part in the preliminary meetings for the establishment of the Democratic Federation, the forerunner of the Social Democratic Federation. She joined the first executive committee. Already, in anticipation of the federation's aims, she had given practical support to labour candidates for parliament. She personally attended on George Odger, the first labour candidate, during his last illness in 1877.
Miss Taylor consistently advocated female suffrage, believing that it would improve the morals of the people. But on 15 August 1878, writing from Avignon, she positively denied a rumour that she intended to seek nomination as a parliamentary candidate for Southwark. In 1885, however, special circumstances led her to essay a parliamentary candidature. Mr. W. A. Coote, the secretary of the Vigilance Association, with the objects of which Miss Taylor closely associated herself, sought nomination as liberal candidate for North Camberwell, but was finally set aside by the party organisers. By way of protest, Miss Taylor took Mr. Coote's place. Her programme included just and better laws for women, the prevention of war, and 'less work and better pay' for the working classes. A letter of support from Henry George advocating her candidature was widely circulated during her campaign. George Jacob Holyoake was an active worker for her. She carried on her campaign amid much turbulence until the nomination day, when the returning officer refused to receive either the nomination papers or the cash deposit for his expenses. In her electoral contest, Miss Taylor attempted what no woman had done before.
Soon afterwards she relinquished public work, owing to age and failing health, and retired for some nineteen years to her house at Avignon, where she had invariably spent her holidays and where she endeared herself to the people by her generous benefactions. The stress of work told on her appearance as well as on her health. At the end of 1904, she returned to England, and under the care of her niece, Miss Mary Taylor, and settled at Torquay. She died there on 29 January 1907, and was buried in the Torquay cemetery.
At the instance of Lord Morley of Blackburn, Miss Taylor, in 1904, presented Mill's library to Somerville College, Oxford.