Hardie was a capable family physician and popular with patients in all levels of society. He won many distinctions and became Queensland president of the British Medical Association in 1910 and 1920. He was a foundation member of the University of Queensland Senate between 1911 and 1916 and chaired the Emmanuel College Council from 1911 to 1940. He joined the Royal Army Medical Corps and served with it in France in 1915-16. Hardie was a staunch Presbyterian and after the war he became the first chairman of the Presbyterian and Methodist Schools Association. He was an honorary physician for years to the Hospital for Sick Children, the Lady Bowen Hospital and the Lady Lamington Hospital and also served on the Central Board of Health from 1894 to 1915 and the Medical Board of Queensland from 1894 to 1934. He published numerous journal articles and one book in 1893, Notes on Some of the More Common Diseases in Queensland in Relation to Atmospheric Conditions.