She was born in Kingstown (now Dún Laoghaire) in County Dublin, and raised in Dungarvan, County Waterford. She was educated in Switzerland and afterwards studied at the Metropolitan School of Art in Dublin and in Paris at the Académie Julian.
She worked mostly as a portraitist. She was also associated with the stained glass movement, founding a stained glass workshop, An Túr Gloine, in 1903. Some of her stained glass work was commissioned from as far as New York, including a window at Christ Church, Pelham dedicated to the memory of Katharine Temple Emmet and Richard Stockton Emmet, grandson of the Irish patriot, Thomas Addis Emmet. Through her talent and energy, and owing to her friendship with the Gore-Booths, she was very successful in obtaining commissions, famously commenting
- "I went through the British aristocracy like the measles."
In 1977 Bruce Arnold noted
- "some of her finest and most sensitive work was not strictly portraiture, for example, An Irish Idyll in the Ulster Museum, and Le Petit Déjeuner (in the National Gallery of Ireland)."
Sarah Purser became wealthy through astute investments, particularly in Guinness. She was very active in the art world in Dublin and was involved in the setting up of the Hugh Lane Municipal Gallery, persuading the Irish government to provide Charlemont House to house the gallery.
In 1923 she became the first female member of the Royal Hibernian Academy.
Until her death she lived for years in Mespil House, a Georgian mansion with beautiful plaster ceilings on Mespil Road, on the banks of the Grand Canal. It was demolished after she died and developed into apartments. She was buried in Mount Jerome Cemetery.
- National Gallery of Ireland (1987). Irish Women Artists: From the Eighteenth Century to the Present Day. National Gallery of Ireland. ISBN 978-0-903162-40-1.
- Sarah Purser at the Princess Grace Irish Library
- Bruce Arnold (1977). Irish art: a concise history (2 ed.) London: Thames and Hudson. ISBN 0-500-20148-X.
- John O'Grady (1996). The Life and Work of Sarah Purser Four Courts Press. ISBN 1-85182-241-0.