Born in Geelong, Victoria in 1902, Ralph Malcolm Warner studied commercial art at Geelong, Melbourne and Sydney Technical schools. He began his career in 1926, working as an advertising artist and illustrator, but also produced watercolours and etchings, which he exhibited at commercial galleries in Melbourne. As a watercolourist, Warner was self-taught and developed a firm, controlled style.
In 1941, Warner enlisted for military service and worked for the Australian Army's Southern Command as a camoufleur. During 1942, he was transferred to the Military Intelligence Corps. There he used his skills as a commercial artist, producing posters that urged Australians to observe the requirements of wartime security. They were widely displayed in shops, hotels, railway stations, public thoroughfares and in military establishments.
Commencing as an official war artist in 1944, Warner covered the activities of the RAAF in Canada, the United States and the Bahamas. His first mission, however, was a brief visit to Papua New Guinea, where he recorded Australian operations against the Japanese. His landscapes of war in the tropics were subsequently published in two servicemen's Christmas books. Arriving in Canada in July 1944, he began a six-month tour of the region, visiting 24 air stations from Calgary, Alberta in the west to Greenwood, Nova Scotia in the east. Despite conditions that included freezing temperatures and troubles in obtaining art supplies, Warner completed nearly 100 watercolours.
His major assignment as a war artist was to record the activities of Australian airmen training in Canada under the Empire Air Training Scheme (EATS). Established in 1939, EATS coordinated air training across the British Empire, with the most advanced training being undertaken in Canada. During his time in Canada, Warner recorded the activities of the training scheme, as well as depicting Canada's changing landscape from summer through autumn and into winter. His images of buildings, landscapes, planes in flight, servicemen and snow scenes are both documentary and expressive, revealing a strong sense of colour and design.
The difficulties of busy air stations, extreme cold and constant movement meant he had to adapt his technique to a less spontaneous style than that of his Australian works. In Canada, Warner made drawings and notes outdoors, finishing his works indoors, often in hotel rooms. Before returning to Australia in February 1945, a number of his paintings were exhibited with works by another Australian war artist, Dennis Adams, at the Canadian National Gallery in Ottawa.
Back in Australia, Warner continued to work as a war artist, touring country areas of New South Wales and Victoria to record the civil and industrial war effort and food production. After the Second World War, Warner made a successful return to commercial art, designing posters, murals and postage stamps and illustrating books. During the 1950s, he gained a reputation as an outstanding watercolourist, winning many prizes.