Mademoiselle Augustine Soubeiran was the daughter of French Huguenot educationists. She attended Madame Trolliet's finishing school at Lausanne, Switzerland, in the mid-1870s and migrated to Sydney after the death of her parents to work as a governess. Following her visit to France in 1886, Mlle Soubeiran became one of the first teachers at Louisa Gurney's Fernbank School in Edgecliff. In 1891, as the school was relocated to larger premises at Kambala, Bellevue Hill.
Mlle Soubeiran taught French at Kambala and also at nearby Ascham, Darling Point. In 1895 she was a founder of the Alliance Française which established prizes for French conversation. In 1911 she was appointed officier de l'Instruction Publique.
On the outbreak of World War I, with Louisa Gurney's backing Mlle Soubeiran initiated the French-Australian League of Help; as its secretary she assisted in establishing one of the largest patriotic organizations in Australia. At the end of 1917, paying her own expenses, she left for France to distribute the accumulated resources of the league's funds. Based in Paris, she dispensed money and set up a depot for clothes from Australia. In 1918 she came back with the diplomatic mission of General Pau to tell Australians of the 'heartfelt, tearful thanks of my people' which is reprinted in part in The School Paper for Grades VII and VIII, August, 1919. She returned to France again in January 1919 and spent months touring the war-devastated districts, distributing further funds and assisting in reconstruction. Late in the year she was joined by Louisa Gurney. In December 1920, they returned to New South Wales to live at Bowral.
Augustine Soubeiran died, unmarried, on 31 May 1933 at Darlinghurst, Sydney, and was cremated. Awarded the Légion d'honneur posthumously in July, she had bequeathed four special pieces of furniture to the National Art Gallery of New South Wales. Lucy Norman's water-colour sketch of Augustine at Lausanne is held by Kambala.