BACKGROUND: People living in low-income settings facing humanitarian crises are at risk for comorbid cardiovascular disease (CVD) and mental health (MH) illness, yet there are limited population-based data available. METHODS: We estimated CVD-MH illness comorbidity and associated risk factors using enrollment data from the Haiti Cardiovascular Disease Cohort Study (2019-2021). Adults aged >18 years were recruited using multistage random sampling across Port-au-Prince. Prevalent CVD (hypertension, heart failure, stroke, or myocardial infarction) was adjudicated by a physician panel integrating clinical examinations, imaging, and laboratory data. Prevalent MH illness was defined as depression symptoms (Patient Health Questionnaire 9 score >5) or stress (Perceived Stress Score >5). We conducted multivariable Poisson regression to analyze the association between risk factors (age, sex, low income, education, smoking, alcohol consumption) and the outcome of prevalent CVD-MH illness. RESULTS: Among 2993 adults in this analysis, the median age was 40 years, 42% were women, and 70% earned an income <1 USD per day. CVD-MH illness comorbidity prevalence was 30% (95% CI, 28-32), with CVD prevalence 34% and MH 85%. In multivariable regression, older age (‚â•60 versus <40 years; adjusted prevalence ratio, 5.79 [95% CI, 4.57-7.38]), female sex (female versus male sex: adjusted prevalence ratio, 1.22 [95% CI, 1.06-1.42]), and lower education (secondary versus primary education: adjusted prevalence ratio, 1.46 [95% CI, 1.24-1.71]) were significantly associated with CVD-MH illness after adjusting for all other factors. CONCLUSIONS: CVD-MH illness comorbidity is highly prevalent in urban Haiti, especially among older adults and women. These findings underscore the need for integrated, contextually adapted approaches to address multimorbidity in crisis-affected low- and middle-income countries.