Background Improving equitable health outcomes needs a further understanding of the social, economic, political, and legal determinants that shape human health and well-being, especially in the poor and marginalized communities in urban slums. Vulnerability represents a group of adverse social determinants that put a household at a greater risk of falling ill. The objective of this study was to determine the magnitude of health, residential, social, and occupational vulnerabilities amongst households in two urban slums in Mumbai, assess the sociodemographic factors associated with health vulnerability, and ascertain the linkage between health vulnerability and other vulnerabilities. Methods A cross-sectional survey was conducted from May to August 2021 in the urban slums of Mumbai. One Urban Primary Health Center area each in two wards (M/East and G/North) of Mumbai city mostly inhabited by people living in slums was purposively selected. A total of 15,796 households were included in the vulnerability assessment survey. Four kinds of vulnerability (health, social, residential, and occupational) indices were created based on survey responses. Results High residential vulnerability was estimated in 73.5%, (95% C.I. 72.8, 74.2), high social vulnerability in 67.9% (95% C.I. 67.2, 68.7), and high occupational vulnerability in 59.5%, (95% C.I. 58.7, 60.2) households. The presence of health vulnerability was observed in 39.6% (95% C.I. 38.8, 40.4) households. On adjusted analysis, social, residential, and occupational vulnerability were all statistically significant predictors of health vulnerability (p<0.001). The health vulnerability increased by 0.492 units for each unit increase in social vulnerability, 0.605 for each unit increase in residential vulnerability, and 0.081 units for each unit increase in occupational vulnerability. Conclusions Health vulnerability is present in nearly four out of ten households in the urban slums of Mumbai, while a majority of the households experience residential, social, and occupational vulnerability. Overcrowding and poor ventilation were nearly universal, with a high burden of poor sanitation and hygiene.