Kosara Bokšan was born in Berlin in 1925.

Three years later, the family moved to Belgrade. She took art classes at Mladen Josić's school at the Kolarac People's University, then in Zora Petrović's studio in 1944. She entered the Academy of Fine Arts in Belgrade in 1945, in Ivan Tabaković's class. She was a member of the Zadar group (1947) consisting of seven students from the Academy of Fine Arts, including her future husband, Petar Omčikus. With Omčikus, she went to Rijeka where she lived and painted between 1948 and 1951. She had her first solo exhibition at the ULUS gallery in Belgrade in 1952.

She was a member of the artist group Jedanaestorica (Eleven Artists). In 1952, she moved to Paris with Petar Omčikus and the same year participated in the exhibition of Yugoslav women artists at the Salon of Women Painters and Sculptors in London. She has presented personal exhibitions in Lille, Paris, Strasbourg, Rome, Belgrade, Zagreb, Novi Sad, etc. During her artistic career, she participated in many important group exhibitions and art events such as the Salon d'Octobre in Belgrade, the Salon de Mai (Salon de Mai) and the Salon des Réalités Nouvelles in Paris.

In the 1960s, in Vela Luka, on the island of Korčula in Croatia, Kosa Bokšan and Petar Omčikus built a house with a studio. Thanks to their commitment, three international meetings of artists took place between 1968 and 1972. Kosara Bokšan's two most important retrospective exhibitions were organized at the Gallery of Visual Arts – Rajko Mamuzić Endowment Collection in Novi Sad in 1990 and at the Museum of Contemporary Art in Belgrade in 2001.

She died in 2009.