Karen Helms studied medicine at the University of Sydney and after graduating in 1922 held RMO appointments at various hospitals in Sydney between 1922 and 1927. Between August 1927 and June 1928 she gained clinical experience in London, Vienna and Copenhagen, following which she returned to private practice in Sydney until 1934.

In 1930 she was appointed medical officer and secretary to the Infantile Paralysis Committee which was formed in that year to facilitate the diagnosis of poliomyelitis and assist in its treatment. A second period abroad in 1936 and 1937 gave her further experience in clinical and laboratory medicine and also in poliomyelitis. When the Consultative Council on Infantile Paralysis was formed by the NSW Department of Health she was appointed medical officer to the Council and joined the Department of Health. She worked hard and saw, as a consultant, virtually every suspected case of poliomyelitis in the metropolitan area, particularly during the epidemics of 1937 to 1938 and 1945.

When poliomyelitis was controlled she became a medical officer at Repatriation General Hospital, Concord and turned her attention to pulmonary tuberculosis, still at that time a serious public health problem. She remained a senior medical officer in thoracic medicine until her retirement in 1963 and was well known and respected as a thoracic physician. From 1943 to 1945 she served as a flight-lieutenant in the RAAF at various medical bases in Australia.

Karen Helms was interested in music, theatre and painting, and had a good collection of Australian art. She was a pleasant person and good taste was evident in all she did. Her sister, Lorna Helms, was a well known actress.