Osborn Cornell was born in 1893 at Ballarat, Victoria, the youngest son of Walter Cornell and Mary Elizabeth Cornell (née Glasson). He studied at Pharmacy College in Melbourne to become a chemist. By the outbreak of the First World War, Osborn had become a fully qualified chemist. He enlisted on 18 August 1914 and was allotted to the 2nd Field Ambulance (FA) of the Australian Army Medical Corps. He had already served in the Citizen Forces as a staff sergeant with the Light Horse Field Ambulance at Ballarat. His contingent embarked from Melbourne aboard HMAT Wiltshire on 19 October 1914.

The 2nd FA were sent to Gallipoli in April 1915 and stayed until September. Dispensaries sat within field hospitals, dispensing basic medical treatments for wounded and sick soldiers. In May 1916 Cornell was with the 3rd Australian General Hospital (AGH) at Abbassia. He then served in England until 13 February 1917, when he returned to Australia aboard the Benalla, serving as the ship’s dispenser.

In Australia, he was offered his discharge but voluntarily re-enlisted as a private with the 10th Machine Gun Company. Cornell returned to England on 2 February 1918 and joined his unit in France on 8 June. Cornell was killed during the fighting on 10 August 1918, a man in his unit reporting that “he was killed instantly by a bullet through the chest and was buried where he fell by his mates.” The location of his burial was lost, so Osborn Cornell is commemorated at the Villers-Bretonneux Memorial. He was 25 years old.