Her parents were Benjamin Francis Marks (born 1846), a merchant, and his wife Jane (Jenny) Matilda, née Cohen (1849-1930).

[6] With the outbreak of the First World War, she went to London and worked to assist the Soldiers' and Sailors' Families Association and Belgian refugees.

[6][8] She was one of the founders and president of the Business and Professional Women's Club of Australia[10] and a longtime member of the local League of Nations Union.

[6] The achievement of Marks of being "the first woman to be appointed as an acting professor in New South Wales",[1] makes her one of the first female academics, together with others such as Dorothy Hill, to head a university department in Australia.

In 1962 she established the Gladys Marks Travelling Scholarship which enabled holders to "undertake studies or research for a degree in a university in France".

[13] Marks, along with the feminists Jessie Street and Ruby Rich, was a "mentor" for the future lawyer, public servant and women's rights activist Nerida Josephine Cohen (later Goodman) who was "the second woman (...) to practise at the New South Wales (NSW) Bar".