Marta Zauniūtė was born on 22 March 1875 in Rokaiten[a] in East Prussia to the family of the Prussian Lithuanian activist Dovas Zaunius.

The family had nine children, three sons and six daughters, including Dovas Zaunius (1892–1940) who became the Lithuanian Minister of Foreign Affairs (1929–1934) and Augustė Zauniūtė (1890–1950) who became a medical doctor.

Due to the Lithuanian press ban, these publications were printed in East Prussia and smuggled to Lithuania which was then part of the Russian Empire.

[8] Some authors give the credit for the store to her fiancé Petras Mikolainis [lt]; Zauniūtė herself expressed irritation that he saw her more as a servant than an equal partner.

Because she helped organize the smuggling of social democratic and communist publications, the bookstore was frequently raided by the German police.

She wrote letters to Povilas Višinskis, Jonas Jablonskis, Felicija Bortkevičienė, Kazys Grinius,[8] Jurgis Šaulys,[12] and others.

He had escaped the German police to the United States, but returned to Tilsit in 1901 hoping to continue cultural work and to open a Lithuanian bookstore.

[4] Vincas Kapsukas and Juozas Gabrys also showed romantic interest,[13] but Zauniūtė remained unmarried.

[3] Due to the increasing power of the Nazi Party, she moved to Klaipėda in 1930 to live with her sister Augustė who had a private medical practice in the city.