Kartini was born into an aristrocatic 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.

Kartini's father, RMAA Sosroningrat, was originally the district chief of Mayong. Her mother was MA 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 MA Ngasirah was not of sufficiently high nobility[1], 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, RAA Tjitrowikromo.

Kartini was the fifth child and 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[2]. 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 was 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.