Jellett's art education began at 11 when she received painting lessons from Elizabeth Yeats, Sarah Cecilia Harrison, and Mary Manning, who had a studio on Merrion Row, and whose influence on Irish Artists of the time was considerable.

She decided to become a painter after working under Walter Sickert at the Westminster Technical Institute in London, where she enrolled in 1917 and remained until 1919.

There she worked under André Lhote and Albert Gleizes, encountering cubism and beginning an exploration of abstract art.

The response was hostile, with the Irish Times publishing a photograph of one of the paintings and quoting their art critic as saying of them, 'to me they presented an insoluble puzzle'.

A deeply committed Christian, her paintings, though never strictly representational and sometimes completely non-objective, occasionally have religious titles and may, in some respects, resemble icons in tone and even, on occasion, in the palette.

Along with Evie Hone, Louis le Brocquy, Jack Hanlon, and Norah McGuinness, Jellett co-founded the Irish Exhibition of Living Art in 1944.

Jellett's work was not very well known outside of Ireland, but she was a pioneer of a national avant-garde and strongly supported the encouragement of young Irish artists.

The IMMA decided to evaluate and reexamine the European canon and bring artists like Mainie Jellett to the front line.