One of the leading female artists of the twentieth century. She studied at Nottingham School of Art and in 1898 she moved to Staithes, where she set up a Studio. In 1903 she married the artist Harold Knight and following a short interval painting in Holland, they moved to Newlyn, where they became leading members of the Newlyn School of Artists. In 1919 she moved to St. John's Wood, which was to be the base for the remainder of her life.

An impressionist painter and a member of the Newlyn School of Art, She was the first woman artist to be made a Dame of the British Empire. From 1903 she exhibited at the Royal Academy and in the same year she married the artist Harold Knight (1874 – 1961), changing her surname from Johnson. At first they lived in an artist’s colony in Staines, North Yorkshire, until moving to Newlyn, Cornwall, in 1907.

Although Knight painted various subjects, her reputation was founded on paintings of the ballet and the circus. She painted backstage at the Diaghilev ballet’s sessions in London and took lessons at Tillers dance academy in St Martin’s Lane in order to draw there. She also traveled with the Mills and Carmos Circus. An accomplished portraitist, she painted wartime commissions and was an official war artist at the Nuremburg War Trials.