Healey became interested in all things mechanical at an early age, most particularly aircraft. After leaving school he joined Sopwith Aviation Company from where he volunteered for the Royal Flying Corps (RFC) and earned his "wings" in 1916. During the First World War, he served on anti-Zeppelin patrols and also as a flying instructor.
Shot down by British anti-aircraft fire on one of the first night bomber missions of the war, he was invalided out of the RFC at the age of 18. He returned to Cornwall and took a correspondence course in automobile engineering. After the war, he opened a garage in Perranporth.
He gained a reputation as a consultant engineer and designer and was appointed General Manager of the Triumph Motor Company in 1931. He went on to create the renowned Southern Cross and Dolomite 8 models.
In 1945, he formed the Healey Motor Company, based in an old RAF hangar at Warwick. The company developed the Austin-Healey Sprite motor car in a licensing arrangement with British Motor Corporation in 1959.
When BMC was taken over by British Leyland in 1966, Donald Healey became chairman of Jensen Cars and was made a CBE.