Background: Hypertension is often asymptomatic disease and can lead to lethal complications. So the present study was done with the objective of studying the prevalence and determinants of hypertension and to assess the applicability of the rule of halves in hypertension in the urban slum community. Methods: It was a community based cross-sectional study conducted from April 2010 to March 2012, among people above 18 years of age residing in an urban slum of Mumbai, from Malwani slum. Multistage sampling procedure was employed and total sample size was 1089. Statistical analysis was done by using SPSS 16 software. Frequency distribution was calculated for all the socio-demographic variables and chi-square test was also employed to study the association between risk factors and presence of hypertension. Results: The prevalence of hypertension in the study group was 23.59%. The prevalence of hypertension in males and females was 23.15% and 24.04%, respectively (using blood pressure ≥ 140/90 as Hypertension). Prevalence of hypertension showed a significant positive association with age, family history of hypertension, body mass index, absence of physical activity, smokeless tobacco, tobacco smoking, alcohol, mixed diet. The hypertensives aware of suffering from hypertension were 41.6%. Out of the hypertensives who were aware of suffering from hypertension 55.5% were taking treatment. While only 47.4% of hypertensives who were taking treatment had controlled blood pressure. Conclusion: The prevalence of hypertension in the current study was 23.59% and thus it still remains a major public health concern in urban slum settings. The rule of halves was still prevalent and the awareness about hypertension and its regular treatment should be given to the community.