Horne was a schoolteacher, grazier and politician. He entered the New South Wales Department of Public Instruction in 1887, initially as a pupil teacher at Bombala, after which he was transferred to Coolah Bridge, where he remained until 1899. He then took up a grazing property at Leadville, near Dunedoo. Horne served as the Labor Member for Liverpool Plains, in the New South Wales Legislative Assembly, from 1907 until his controversial resignation in 1911. He was subsequently elected to the New South Wales Legislative Council, where he served as a National, UAP, and Liberal Party member from 1917 until his death in 1955.
During the 1920s and 1930s, Horne wrote the words to a number of patriotic songs which were performed by New South Wales school children at official events. 'A Song for the Bridge' was performed by 12,000 children at the Sydney Cricket Ground in 1932, during celebrations to mark the opening of the Sydney Harbour Bridge.