At the 1902 Queensland elections, Hawthorn, representing the Ministerialists, contested the seat of Enoggera, soundly defeating the sitting Labour member, Matthew Reid. During his time as member, Hawthorn was twice Home Secretary, for eight months in 1907 and for four months in 1908. On 29 October 1908, Hawthorn was appointed Treasurer of Queensland, remaining in the role until his resignation from the Legislative Assembly on 7 February 1911.
