Kartini was born into an aristocratic Javanese family in a time when Java was still part of the Dutch colony, the Dutch East Indies. Kartini's father, Raden Mas Sosroningrat, became Regency Chief of Jepara, and her mother was Raden Mas' first wife, but not the most important one. At this time, polygamy was a common practice among the nobility. She also wrote the Letters of a Javanese Princess.

Kartini's father, R.M.A.A. Sosroningrat, was originally the district chief of Mayong. Her mother was M.A. Ngasirah, the daughter of Kyai Haji Madirono, a teacher of religion in Teluwakur, Jepara, and Nyai Haji Siti Aminah. At that time, colonial regulations specified that a Regency Chief must marry a member of the nobility and because M.A. Ngasirah was not of sufficiently high nobility, her father married a second time to Raden Ajeng Woerjan (Moerjam), a direct descendant of the Raja of Madura. After this second marriage, Kartini's father was elevated to Regency Chief of Jepara, replacing his second wife's own father, R.A.A. Tjitrowikromo. Kartini was the fifth child and second eldest daughter in a family of eleven, including half siblings. She was born into a family with a strong intellectual tradition. Her grandfather, Pangeran Ario Tjondronegoro IV, became a Regency Chief at the age of 25 while Kartini's older brother Sosrokartono was an accomplished linguist.

Kartini's family allowed her to attend school until she was 12 years old. Here, among other subjects, she learnt to speak fluent Dutch, an unusual accomplishment for Javanese women at the time. After she turned 12 she was 'secluded' at home, a common practice among Javanese nobility, to prepare young girls for their marriage. During seclusion girls were not allowed to leave their parents' house until they were married, at which point authority over them was transferred to their husbands. Kartini's father was more lenient than some during his daughter's seclusion, giving her such privileges as embroidery lessons and occasional appearances in public for special events. During her seclusion, Kartini continued to educate herself on her own. Because Kartini could speak Dutch, she acquired several Dutchpen friends. One of them, a girl by the name of Rosa Abendanon, became her very close friend. Books, newspapers and European magazines fed Kartini's interest in European feminist thinking, and fostered the desire to improve the conditions of indigenous women, who at that time had a very low social status.

Kartini's omnivorous reading included the Semarang newspaper De locomotief, edited by Pieter Brooshooft, as well as leestrommel, a set of magazines circulated by bookshops to subscribers. She also read cultural and scientific magazines as well as the Dutch women's magazine De Hollandsche Lelie, to which she began to send contributions which were published. From her letters, it was clear that Kartini read everything with a great deal of attention and thoughtfulness. The books she had read before she was 20 included Max Havelaar and Love Letters by Multatuli. She also read De Stille Kracht (The Hidden Force) by Louis Couperus, the works of Frederik van Eeden, Augusta de Witt, the Romantic - Feminist author Mrs. Goekoop de-Jong Van Beek and an anti-war novel by Berta von Suttner, Die Waffen Nieder! (Lay Down Your Arms!). All were in Dutch.

Kartini's concerns were not just in the area of the emancipation of women, but also the problems of her society. Kartini saw that the struggle for women to obtain their freedom, autonomy and legal equality was just part of a wider movement.

Kartini's parents arranged her marriage to Raden Adipati Joyodiningrat, the Regency Chief of Rembang, who already had three wives. She was married on 12 November 1903. This was against Kartini's wishes, but she acquiesced to appease her ailing father. Her husband understood Kartini's aims and allowed her to establish a school for women in the east porch of the Rembang Regency Office complex. Kartini's only son was born on September 13, 1904. A few days later on September 17, 1904, Kartini died at the age of 25. She was buried in Bulu Village, Rembang.

Inspired by Kartini's example, the Van Deventer family established the Kartini Foundation which built schools for women, 'Kartini's Schools' in Semarang in 1912, followed by other women's schools in Surabaya, Yogyakarta, Malang, Madiun, Cirebon and other areas.

In 1964, President Sukarno declared Kartini's birth date, 21 April, as 'Kartini Day' - an Indonesian national holiday. This decision has been criticised. It has been proposed that Kartini's Day should be celebrated in conjunction with Indonesian Mothers Day, on 22 December so that the choice of Kartini as a national heroine would not overshadow other women who, unlike Kartini, took up arms to oppose the colonisers. In contrast, those who recognise the significance of Kartini argue that not only was she a feminist who elevated the status of women in Indonesia, she was also a nationalist figure, with new ideas who struggled on behalf of her people, including her in the national struggle for independence.

After Kartini died, Mr J.H. Abendanon, the Minister for Culture, Religion and Industry in the East Indies, collected and published the letters that Kartini had sent to her friends in Europe. The book was titled Door Duisternis tot Licht (Out of Dark Comes Light) and was published in 1911. It went through five editions, with some additional letters included in the final edition, and was translated into English by Agnes L. Symmers and published under the title Letters of a Javanese Princess. The publication of Kartini's letters, written by a native Javanese woman, attracted great interest in the Netherlands and Kartini's ideas began to change the way the Dutch viewed native women in Java. Her ideas also provided inspiration for prominent figures in the fight for Independence.

There are some grounds for doubting the veracity of Kartini's letters. There are allegations that Abendanon made up Kartini's letters. These suspicions arose because Kartini's book was published at a time when the Dutch Colonial Government were implementing 'Ethical Policies' in the Dutch East Indies, and Abendanon was one of the most prominent supporters of this policy. The current whereabouts of the vast majority of Kartini's letters is unknown. According to the late Sulastin Sutrisno, the Dutch Government has been unable to track down J. H. Abendanon's descendants.

In her letters, Kartini wrote about her views of the social conditions prevailing at that time, particularly the condition of native Indonesian women. The majority of her letters protest the tendency of Javanese Culture to impose obstacles for the development of women. She wanted women to have the freedom to learn and study. Kartini wrote of her ideas and ambitions, including Zelf-ontwikkeling, Zelf-onderricht, Zelf-vertrouwen, Zelf-werkzaamheid and Solidariteit. These ideas were all based on Religieusiteit, Wijsheid en Schoonheid, that is, belief in God, wisdom, and beauty, along with Humanitarianisme (humanitarianism) and Nationalisme (nationalism). Kartini's letters also expressed her hopes for support from overseas. In her correspondence with Estell "Stella" Zeehandelaar, Kartini expressed her desire to be like a European youth. She depicted the sufferings of Javanese women fettered by tradition, unable to study, secluded, and who must be prepared to participate in polygamous marriages with men they don't know. Kartini also expressed criticisms about religion. She questioned why the Quran must be memorised and recited without an obligation to actually understand it. She also expressed the view that the world would be more peaceful if there was no religion to provide reasons for disagreements, discord and offence. She wrote "Religion must guard us against committing sins, but more often, sins are committed in the name of religion" Kartini also raised questions with the way in which religion provided a justification for men to pursue polygamy. For Kartini, the suffering of Javanese women reached a pinnacle when the world was reduced to the walls of their houses and they were prepared for a polygamous marriage.

It is known from her letters dated October 1902 to Abendanon and her husband that at the age of 23, Kartini had a mind to live a vegetarian life. "It has been for sometime that we are thinking to do it (to be a vegetarian), I have even eaten only vegetables for years now, but I still don't have enough moral courage to carry on. I am still too young." Kartini once wrote. She also emphasized the relationship between this kind of lifestyle with religious thoughts. She also quoted, "Living a life as vegetarian is a wordless prayer to the Almighty."

Kartini loved her father deeply although it is clear that her deep affection for him became yet another obstacle to the realisation of her ambitions. He was sufficiently progressive to allow his daughters schooling until the age of 12 but at that point the door to further schooling was firmly closed. In his letters, her father also expressed his affection for Kartini. Eventually, he gave permission for Kartini to study to become a teacher in Batavia (now Jakarta), although previously he had prevented her from continuing her studies in the Netherlands or entering medical school in Batavia.

Kartini's desire to continue her studies in Europe was also expressed in her letters. Several of her pen friends worked on her behalf to support Kartini in this endeavour. And when finally Kartini's ambition was thwarted, many of her friends expressed their disappointment. In the end her plans to study in the Netherlands were transmuted into plans to journey to Batavia on the advice of Mrs. Abendanon that this would be best for Kartini and her younger sister, Rukmini.

Nevertheless, in 1903 at the age of 24, her plans to study to become a teacher in Batavia came to nothing. In a letter to Mrs. Abendanon, Kartini wrote that the plan had been abandoned because she was going to be married... "In short, I no longer desire to take advantage of this opportunity, because I am to be married..". This was despite the fact that for its part, the Dutch Education Department had finally given permission for Kartini and Rukmini to study in Batavia.

As the wedding approached, Kartini's attitude towards Javanese traditional customs began to change. She became more tolerant. She began to feel that her marriage would bring good fortune for her ambition to develop a school for native women. In her letters, Kartini mentioned that not only did her esteemed husband support her desire to develop the woodcarving industry in Jepara and the school for native women, but she also mentioned that she was going to write a book. Sadly, this ambition was unrealised as a result of her premature death in 1904 at the age of 25.