At the 2011 census, there were people in the Muswellbrook Shire local government area, of these 51.7 per cent were male and 48.3 per cent were female. Aboriginal and Torres Strait Islander people made up 5.4 per cent of the population, which was significantly higher than the national and state averages of 2.5 per cent. The median age of people in the Muswellbrook Shire was 34 years, which was lower than the national median of 37 years. Children aged 0 – 14 years made up 22.8 per cent of the population and people aged 65 years and over made up 10.6 per cent of the population. Of people in the area aged 15 years and over, 47.0 per cent were married and 11.8 per cent were either divorced or separated. Population growth in the Muswellbrook Shire between the 2001 census and the 2006 census was 3.25 per cent; and in the subsequent five years to the 2011 census, population growth was 3.64 per cent. When compared with total population growth of Australia for the same periods, being 5.78 per cent and 8.32 per cent respectively, population growth in the Muswellbrook Shire local government area was approximately half the national average. The median weekly income for residents within the Muswellbrook Shire was marginally higher than the national average. At the 2011 census, the proportion of residents in the Muswellbrook Shire local government area who stated their ancestry as Australian or Anglo-Saxon exceeded 81 per cent of all residents. In excess of 68% of all residents in the Muswellbrook Shire nominated a religious affiliation with Christianity at the 2011 census, which was considerably higher than the national average of 50.2 per cent. Meanwhile, as at the census date, compared to the national average, households in the Muswellbrook Shire local government area had a significantly lower than average proportion where two or more languages are spoken ; and a significantly higher proportion where English only was spoken at home.
Muswellbrook Shire Council is composed of twelve Councillors elected proportionally as a single ward. All Councillors are elected for a fixed four-year term of office. The Mayor is elected by the Councillors at the first meeting of the Council. The most recent election was held on 10 September 2016 and the makeup of the Council is as follows: The current Council, elected in 2016, in order of election, is:
Mayors
The following is a list of mayors since the Shire of Denman amalgamated with the Municipality of Muswellbrook to form Muswellbrook Shire Council on 1 July 1979.
