The electorate was created in 1856 for the First Parliament under the name Maneroo, derived from an Aboriginal name for the area, now spelt Monaro. It was renamed Monara for the second Parliament in February 1858. The spelling was changed to Monaro from 1877 until 1894. It elected two members between 1880 and 1894. In 1894, single-member electorates were introduced statewide and part of the electorate, (including Bombala), was absorbed into Eden-Bombala. At this time the spelling was changed to Manaro. The 1903 New South Wales referendum required the number of members of the Legislative Assembly to be reduced from 125 to 90,[2] the district was expanded to include parts of Queanbeyan and the abolished seat of Eden-Bombala and the spelling reverted to Monaro.[3] In 1913, it absorbed much of the electoral district of Queanbeyan, including Queanbeyan, which is its major city. In 1920, with the introduction of proportional representation, it was absorbed into Goulburn, along with Bega. It was recreated in 1927.
Nationals member Nichole Overall made history in 2022 by being elected as the first female representative of the Monaro. Overall's husband was previously mayor of the City of Queanbeyan.