Browne was educated at Saint Felix School in Southwold and Somerville College. After achieving a second-class honours in modern history at the University of Oxford in 1902, she became a schoolteacher. Later she worked under Mary Sheepshanks at Morley College for Working Men and Women. She was also a member of the Women Social & Political Union.
On 23rd November, 1911, Dora Marsden, Grace Jardine and Mary Gawthorpe published the first edition of The Freewoman. The journal caused a storm when it advocated free love and encouraged women not to get married. The journal also included articles that suggested communal childcare and co-operative housekeeping. Stella Browne became one of the journal's most important contributors.
Mary Humphrey Ward, the leader of Anti-Suffrage League argued that the journal represented "the dark and dangerous side of the Women's Movement". According to Ray Strachey, the leader of the National Union of Suffrage Societies (NUWSS), Millicent Fawcett, read the first edition and "thought it so objectionable and mischievous that she tore it up into small pieces". Whereas Maude Royden described it as a "nauseous publication". Edgar Ansell commented that it was "a disgusting publication... indecent, immoral and filthy."
The most controversial aspect of the The Freewoman was its support for free-love. On 23rd November, 1911 Rebecca West wrote an article where she claimed: "Marriage had certain commercial advantages. By it the man secures the exclusive right to the woman's body and by it, the woman binds the man to support her during the rest of her life... a more disgraceful bargain was never struck."
On 28th December 1911, Dora Marsden began a five-part series on morality. Dora argued that in the past women had been encouraged to restrain their senses and passion for life while "dutifully keeping alive and reproducing the species". She criticised the suffrage movement for encouraging the image of "female purity" and the "chaste ideal". Dora suggested that this had to be broken if women were to be free to lead an independent life. She made it clear that she was not demanding sexual promiscuity for "to anyone who has ever got any meaning out of sexual passion the aggravated emphasis which is bestowed upon physical sexual intercourse is more absurd than wicked."
Dora Marsden went on to attack traditional marriage: "Monogamy was always based upon the intellectual apathy and insensitiveness of married women, who fulfilled their own ideal at the expense of the spinster and the prostitute." According to Marsden monogamy's four cornerstones were "men's hypocrisy, the spinster's dumb resignation, the prostitute's unsightly degradation and the married woman's monopoly." Marsden then added "indissoluble monogamy is blunderingly stupid, and reacts immorally, producing deceit, sensuality, vice, promiscuity and an unfair monopoly." Friends assumed that Marsden was writing about her relationships with Grace Jardine and Mary Gawthorpe.
On 21st March 1912 Stella Browne wrote about her views on free-love in The Freewoman: "The sexual experience is the right of every human being not hopelessly afflicted in mind or body and should be entirely a matter of free choice and personal preference untainted by bargain or compulsion."
The articles on sexuality created a great deal of controversy. However, they were very popular with the readers of the journal. In February 1912, Ethel Bradshaw, secretary of the Bristol branch of the Fabian Women's Group, suggested that readers formed Freewoman Discussion Circles. Soon afterwards they had their first meeting in London and other branches were set up in other towns and cities.
Stella Browne was an active member of the Freewoman Discussion Circles. Talks included Edith Ellis (Some Problems of Eugenics), Rona Robinson (Abolition of Domestic Drudgery), C. H. Norman (The New Prostitution), Huntley Carter (The Dances of the Stars) and Guy Aldred (Sex Oppression and the Way Out). Other active members included Grace Jardine, Harriet Shaw Weaver, Edmund Haynes, Harry J. Birnstingl, Charlotte Payne-Townshend Shaw, Rebecca West, Havelock Ellis, Lily Gair Wilkinson, Françoise Lafitte-Cyon and Rose Witcup.
In 1913 Stella Browne, joined forces with George Ives, Edward Carpenter, Magnus Hirschfeld and Laurence Housman to establish the British Society for the Study of Sex Psychology. The papers she gave to the society, included "The sexual variety and variability among women and their bearing upon social reconstruction" (1915).
Browne wrote in 1917: "The psychology of homogenic women has been much less studied than that of inverted men. Probably there are many varieties and subtleties of emotional fibre among them. Some very great authorities have believed that the inverted woman is more often bisexual - less exclusively attracted to offer women - than the inverted man. This view needs very careful confirmation, but if true, it would prove the greater plasticity of women's sex-impulse. It has also been stated that the invert, man or woman, is drawn towards the normal types of their own sex... Certainly, the heterosexual woman of passionate but shy and sensitive nature, is often responsive to the inverted woman's advances, especially if she is erotically ignorant and inexperienced. Also many women of quite normally directed (heterosexual) inclinations, realise in mature life, when they have experienced passion, that the devoted admiration and friendship they felt for certain girl friends, had a real, though perfectly unconscious spark of desire in its exaltation and intensity; an unmistakable, indefinable note, which was absolutely lacking in many equally sincere and lasting friendships."
Browne published Studies in Female Inversion in 1918: "This problem of feminine inversion is very pressing and immediate, taking into consideration the fact that in the near future, for at least a generation, the circumstances of women's lives and work will tend, even more than at present, to favor the frigid (sexually repressed) and next to the frigid, the inverted types. Even at present, the social and affectional side of the invert's nature has often fuller opportunity of satisfaction than the heterosexual woman's, but often at the cost of adequate and definite physical expression. I think it is perhaps not wholly uncalled-for, to underline very strongly my opinion that the homosexual impulse is not in any way superior to the normal; it has a fully equal right to existence and expression, it is no worse, no lower; but no better."
According to her biographer, Lesley A. Hall: "Browne emphasized the need for women to speak about their own experiences. In both principle and practice Stella was a convinced believer in free love, known to have had various lovers, certainly some male, and possibly some female, though these cannot be reliably identified."
Browne, a member of the Malthusian League, campaigned strongly for birth control and abortion. She was also a member of the Divorce Law Reform Union, the No-Conscription Fellowship, the Humanitarian League, the Fabian Society, the Labour Party and the Communist Party of Great Britain.