Objective This study aimed to determine the usability of the EMPOWER-SUSTAIN Self-Management Mobile App© and evaluate the factors associated with its usability among patients with cardiovascular risk factors in primary care. Methodology This was a cross-sectional study, conducted among patients aged ≥ 18 years with cardiovascular risk factors attending a university primary care clinic. Patients were given the app to use for at least three months. Those who fulfilled the eligibility criteria were recruited. Data gathered were on sociodemographic, clinical characteristics, self-management support by doctors, utilisation of the app at home and social support in using the app. The previously translated and validated Malay version of the mHealth App Usability Questionnaire was used to measure usability. The mean usability score was calculated and linear regressions analysis was conducted to determine the factors associated with the usability of the app. Results A total of 247 patients with at least one cardiovascular risk factor(s) were recruited. The mean age was 60.2 (±8.2). The majority were Malays (86.2%) and half of them were males (52.2%). The total mean (±SD) usability score was 5.26 (±0.67) indicating a high usability of the app. Usability of the app declined with increasing age in the simple linear regressions analysis. The multiple linear regressions yielded that being Malay ( b = 0.31, 95% CI 0.08,0.54), using the app at home to understand their medications ( b = 0.33, 95% CI 0.12,0.53) and having social support from family members and friends ( b = 0.28, 95% CI 0.07,0.49) were significantly associated with higher usability of the app. Conclusion The usability of the EMPOWER-SUSTAIN Self-Management Mobile App© was high among patients with cardiovascular risk factors in our primary care clinic. This finding supports the widespread use of this app among our patients. Involvement of family members and friends should be encouraged to improve the usability of the app.