Horsley moved to Auckland after graduation taking up a position as a house surgeon at
Auckland Hospital in 1899. She was the first woman doctor registered in Auckland and the first woman employed at Auckland Hospital, where she held a position as honorary
bacteriologist and pathologist, until Constance Frost was appointed. From 1936–1946, she was an anaesthetist at the Mater Misericordiae Hospital, and worked privately for surgeons including Sir
Carrick Robertson and James Hardie Neil. Horsley worked throughout the plague scare of 1900 and the
1918 influenza epidemic, and was a member of the medical relief team after the
Hawke's Bay earthquake of 1931, in which hundreds were killed and thousands injured. During the economic depression of the 1930s, Horsley became the regular doctor for the non-denominational Dock Street Mission medical clinic, which had been opened to serve patients who could not afford to pay for medical care. Her dedication to the mission led to her appointment as OBE in 1939. Horsley died in
Papatoetoe on 7 November 1957. She was survived by three daughters and a son; her husband had died in 1950. == Honours ==