Born at Mount Eden, Auckland, on 15 February 1883, Eunice Harriett Garlick (registered as Harriett Eunice) was the seventh of ten children of English-born parents Ellen Green and her husband, Richard Knight Garlick. Her father was a kauri-gum merchant and the family lived comfortably in a large house with spacious grounds on Khyber Pass Road. After attending Whanganui Girls' College from about 1895 to 1900, Una, as she was known, returned to live with her family. She never married and it was a matter of family pride that neither she nor her two unmarried sisters, Florence and Hilda, were ever forced to earn a living.
Una Garlick's parents and siblings were keenly interested in music and needlework, and encouraged her artistic pursuits. Among her friends was Edith Whitelaw, a first violinist with the Auckland Choral Society orchestra and later leader of the Auckland Orchestral Society. Una too became an accomplished violinist and played with Whitelaw in Auckland's Bohemian Orchestra. But her principal interest was photography, which she regarded as far more than a mere hobby or indulgence. She brought to it a professional attitude and serious dedication.
It is not known exactly when Una Garlick began producing photographic work, but she established her first darkroom under the conservatory of her family's Khyber Pass Road home. Some years after the death of Richard Garlick in 1899, Una moved with her mother and two unmarried sisters to a smaller house in Remuera Road, where she again set up a darkroom. They lived there until after Ellen's death in 1931, when the sisters bought a new home in Ormonde Road, Remuera; Una once again installed a darkroom.
Una Garlick's extended family and friends provided her with work recording weddings and family gatherings. Occasional commissions for portrait and other work, the sale of exhibition prints and competition prize money appear to have been her only earned income. Her quest for interesting subjects took her throughout New Zealand with her car and camera, and she embarked on a number of overseas trips with one or other of her sisters.
Involvement in photographic societies provided Garlick with the stimulation of competition and critical comment. She was the first woman nominated as a member of the Auckland Camera Club (later the Auckland Photographic Society) after it changed its rules to admit 'lady members' in 1921. Between 1922 and 1927 she played a prominent role in the club, winning many of its monthly competitions and receiving its annual medal in 1926. At the height of her career Garlick was widely acknowledged as a photographer of considerable ability. Between 1925 and 1931 she had more than 30 prints accepted by international salons in London, Paris, Boston and Vancouver, and she became an associate member of the Royal Photographic Society of Great Britain.
Along with other New Zealand photographers, particularly Gerald E. Jones and George Chance, Una Garlick identified with the British-based Pictorialist movement, which promoted photography as art, stressed the importance of deliberate, well-balanced composition, and employed various techniques to capture mood and atmosphere. She produced landscapes of considerable merit, but is best remembered for a series of evocative portraits of Māori women. One of these studies, entitled 'Georgina', appeared in the American Annual of Photography in 1930.
Una Garlick died of cancer at her home in Ormonde Road, Remuera, on 17 March 1951. She was a strong personality, described by her family as frank and forthright, and her photographic career demonstrated her creative discipline and dedication. The Auckland Institute and Museum holds a number of Garlick's negatives and prints; other prints are held at the Rotorua Art and History Museum and the Alexander Turnbull Library, Wellington.