95.3% of the population only speak English at home, with the most common languages spoken other than English being Mandarin, German and French. The median age of Killcare Heights is 47, significantly above the median age of NSW and Australia, which is 38. 41.4% of the population described themselves as without a religion, while 21.1% of people described themselves as Catholic, and 17.1% of the population described themselves as Anglican. Residents also self-identify as members of the Uniting Church, Presbyterian and Pentecostal churches.
- Australian Bureau of Statistics (27 June 2017). "Killcare Heights (State Suburb)". 2016 Census QuickStats. Retrieved 10 November 2019.