She also became actively working as a designer and was a founder member of the Arts & Crafts Exhibition Society. She participated in their inaugural exhibition at the New Gallery in London in 1888 and continued to exhibit with them for several years. She also exhibited at the Society of Women Artists in London in 1896, 1929 and 1932, and was represented in the British Arts & Crafts Section at the International Exhibition in Ghent in 1913, and in the exhibition Arts Décoratifs de Grande-Bretagne et d'Irlande at the Palais du Louvre in Paris in 1914. She contributed needlework to the 10th annual exhibition of the Cumberland and Westmorland Society of Arts and Crafts in Carlisle in 1906. In 1907 she was a co-founder of the Women’s Guild of Arts.

She was primarily known for her work as an embroiderer, a subject on which she wrote numerous articles, a book, 'Decorative Needlework' (1893), and lectured extensively. She also designed jewellery, wallpapers, lettering, and book decoration. May Morris was for many years a friend of the bookbinder Katharine Adams and in March 1905 they held a joint exhibition of jewellery and embroidery in Mayfair, London. Morris's work as a book decorator included the decoration of her father's book 'Love is Enough' and embroidered binding for 'A Study of Dante'. She designed the lettering used by T. J. Cobden-Sanderson for some of his books, for the spine of 'Fabian Essays in Socialism' (1889) and for her own book. She was a member of the Fabian Society and designed a banner for the Fabian Women's Group which was carried in a procession of the National Union of Women's Suffrage Societies on 13 June 1905.

From 1897 to 1910 she taught at the Central School of Arts and Crafts in London and occasionally at Birmingham School of Art from 1896.

In 1890 May Morris married Henry Halliday Sparling (1860-1924), Secretary of the Socialist League. The marriage broke down and in 1890 they divorced. She died at Kelmscott Manor, Oxfordshire on 17 October 1938.