Children are especially vulnerable to the effects of anthropogenic climate change, yet very few studies assess the impacts on Australian children. Australia is a vast country encompassing many climate variations, with aggregated nation-wide health data available. We have assessed the relative contribution of climate and socioeconomic variables on the following child health outcomes: child mortality, low birth weight, low Apgar scores and prevalence of asthma in children under five years of age. High temperature extremes, proximity to bushfires, household income, nitrogen dioxide pollution and household size were the leading contributors to poor health outcomes in Australian children.