Born in the Victorian city of Ballarat, she studied under a leading Australian Impressionist, Frederick McCubbin, at the National Gallery of Victoria Art School from 1902 to 1905 and was an early member of the Melbourne Society of Women Painters and Sculptors.
Following the death of her father in 1907, Rix, her only sibling Elsie and her mother travelled to Europe where she undertook further study, first in London and then Paris.
The family evacuated from France to England after the outbreak of World War I.
A period of personal tragedy followed, as Rix's sister died in 1914, then her mother in 1915.
In 1916 she met and married George Matson Nicholas, only to be widowed the next month when he was killed on the Western Front.
Returning to Australia in 1918, Rix Nicholas once more took up professional painting, and held an exhibition of over a hundred works at Melbourne's Guild Hall.
Many sold, including In Picardy, purchased by the National Gallery of Victoria.
Following a period painting in rural locations in the early 1920s, Rix Nicholas returned to Europe.
Other exhibitions, such as the International Society of Sculptors, Painters and Gravers, and the Royal Academy of Arts, both in London, soon hosted her work.
The couple settled at Delegate, New South Wales; their only child, a son named Rix Wright, was born in 1930.
Though she continued to paint significant works including The Summer House and The Fair Musterer, Rix Nicholas, a staunch critic of modernism and disdainful of emerging major artists such as Russell Drysdale and William Dobell, grew out of step with trends in Australian art.
Her pictures followed a conservative modern style, portraying an Australian pastoral ideal, and reviews of her exhibitions grew more uneven.
She held her last solo show in 1947.
Rix Nicholas remained at Delegate until her death in 1961.
Her works are held in most major Australian collections, including the Art Gallery of South Australia, Australian War Memorial, National Gallery of Australia, National Gallery of Victoria, and the Queensland Art Gallery.