Born in Edinburgh, Dorothy Johnstone was the daughter and niece of landscape artists. Following her studies at Edinburgh College of Art (ECA), Dorothy travelled to Italy on a scholarship award and to Paris. Through her friendship with Cecile Walton, the daughter of E.A. Walton, she became acquainted with members of the Glasgow School.
In 1914 Dorothy became a teacher at ECA and in 1915 she started visiting Kirkcudbright. She exhibited with both the Edinburgh Group and her friend Cecile in the early 1920s. Dorothy married her colleague, David Sutherland, in 1924, and with that she was forced to resign her teaching post. The Sutherlands moved to Aberdeen in 1933 when David was made head of Gray's School. Dorothy painted landscapes and portraits, particularly of children.
She was a talented draughtswoman and her style was free and relaxed, whether using oil, watercolour, pencil or chalk. Dorothy Johnstone became an Associate of the RSA in 1962.