Urban slum dwellers are not only prone to develop communicable diseases but also to non-communicable disease (NCDs). The extent and magnitude of NCDs among slum dwellers is largely unknown in Nigeria. A total of 964 adults aged 20-81 years (male 330 and female 634) residing in the urban slum of Ajegunle in Lagos State, Nigeria were studied to determine the prevalence of hypertension and associated factors. The overall prevalence of hypertension was 38.2 %. Of the 368 respondents identified as having hypertension, only 50 (5.2 %) respondents were previously aware of their diagnosis. Of the 50 known hypertensive patients, 48(96 %) had poor control of their high blood pressure. The socio-demographic factors significantly associated with hypertension status were age, sex, education, religion, BMI, and marital status. The study concludes a high prevalence of hypertension among urban slums dwellers in Lagos. The need for government to develop policies for the control of hypertension, improve access to early diagnosis and provide an enabling socioeconomic environment while promoting healthy living.