Objective. To study the implications of household tobacco and alcohol use on child health and women’s welfare using a gender lens in Ethiopia, India, Indonesia, Jordan, Kenya, and Nigeria with varied geographical and cultural characteristics in the pattern of tobacco and alcohol use. Methods. We identified child health and women’s welfare outcomes that may be impacted by tobacco and alcohol use, with a focus on the crowding-out effects on household resource allocation. For child health indicators, we focussed on engagement in preventative care, nutrition, and responses to acute illness. For women, we focused on access to resources for health-seeking and intimate partner violence (IPV). We used logistic regression to determine the association between household gender tobacco and/or alcohol use on child health and women’s welfare, using data from six nationally-representative Demographic and Health Surveys, with each having a sample size of 5000–30,000 households and conducted after 2010. Results. Children in households where men and women use tobacco are significantly less likely to receive the full schedule of Diphtheria-Pertussis-Tetanus (DPT) vaccine in India, Indonesia, and Jordan (Odds ratio or OR; ORIndia = 0.67, p < 0.001; ORIndonesia = 0.55, p = 0.028; ORJordan = 0.45, p = 0.048), and all basic vaccinations as well as receive appropriate treatment for fever/diarrhoea in India and Indonesia (all basic vaccinations: ORIndia = 0.78, p < 0.001, ORIndonesia = 0.43, p = 0.009; treatment for fever/diarrhoea: ORIndia = 0.65, p < 0.001; ORIndonesia = 0.50, p = 0.038). In most countries, women are significantly more likely to experience IPV when their husband/partner uses tobacco and/or alcohol. Conclusions. Across a diverse set of countries with varied cultural characteristics which affect the uptake and use of tobacco and alcohol, tobacco and alcohol use are associated with crowding-out of acute and preventative health-related behaviours and crowding-in of harmful behaviours. This has significant implications for tobacco and alcohol control programmes, and positions tobacco and alcohol control as central to human capital initiatives and in achieving health for all.