Religiosity can be an important factor in women's health-related behaviour, attitudes, and decision-making. Evidence however, regarding the religiosity of mothers and its influence on child health, is scarce. Based on a large population-based cohort in Australia, we aim to examine the religiosity of women in Australia and the association of maternal religiosity with children's health-related quality of life (HRQOL) and lifestyle. Our findings indicate that (1) maternal religious involvement was higher for women with higher education levels, ascertained religious values in decision-making, and abstinence from binge drinking in the household, (2) maternal religiosity positively influenced their children's HRQOL, (3) children of mothers who were more religious had less worries or fewer school-work problems, but the children of mothers with stronger religious beliefs used more internet/computer during the week but had less time playing games on weekends. This study provides additional specificity to inform future health interventions in religious community contexts to enhance the positive influence of maternal religious belief for better development of their children.