Children of problem gamblers are at risk of harm, however, there are no population level estimates as to how many children are currently exposed to parental problem- and at-risk gambling. The current study analysed data from the Household, Income and Labour Dynamics in Australia (HILDA) Survey, a nationally representative survey, to derive the first ever national estimates of the proportion of problem, moderate, and low risk gamblers (as measured by PGSI) in the Australian parent population. It also reports how many children under 15 years of age in Australia are exposed to parental gambling across the gambling risk categories. The results show that 13.7% of all Australian families with dependent children are currently exposed to some level of gambling risk due to parental gambling, and nearly 4% of families with children are exposed to parental moderate risk or problem gambling. This corresponds to almost 200,000 children each year. The results and approach of this study will guide future examination of child wellbeing in families where parents experience problems with gambling. The results are discussed in the context of public health approaches to familial gambling harm.