Upon her move to County Limerick, O'Brien set about supporting the failing Limerick lace industry. She made contact with local lace craftswomen, and provided them with high quality materials as well as her own designs. From this she arranged the sale of the work, using her circle of friends in Dublin and London. O'Brien was a central figure in the foundation of the Private Committee for Promoting Irish Lace, with the support of Alan Cole of the Department of Science and Art, South Kensington and James Brenan RHA. This committee led to the establishment of the lace training school in Limerick in May 1889, and in 1893 on the committee's request her took over the running of the school. When her family moved to New Hall, near Ennis, County Clare, in 1890. In 1895, she established Clare Embroidery, which was run from her home. She was assisted in this endeavour by the O'Briens' children's nurse, a Scotswoman named Mina Keppie, which had the capacity to train up to 15 girls at a time. The business moved with the family to Ballyalla in 1898, and by 1910 they were training up to 27 girls at one time. Both ventures exhibited their work with arts and crafts exhibitions in Ireland, Britain, and America from the 1890s to the 1920s. Amongst these exhibitions were those of the Royal Dublin Society, the Arts and Crafts Society of Ireland, the world fairs in Chicago and St Louis in 1893 and 1904 respectively winning several awards. At Lady Arran's Windsor sale in 1900, both Queen Victoria and the princess of Wales purchased examples of their work.