Son of Major-General Sir Joseph O’Halloran, G.C.B., Bengal Army, he served in the Indian 1840 Army prior to arriving in Adelaide in 1838 at the age of forty-one years. He settled in O’Halloran Hill, was made a J.P., and the following year was appointed one of the four 1843 Honorary Commissioners who administered the Force. He became the first Commissioner of Police in 1840.