BACKGROUND: Traditional, complementary and alternative medicine (TCAM) is used to treat a broad range of conditions. In low- and middle-income countries (LMICs), TCAM use is particularly common among those with low socio-economic status. To better understand the patterns and impact of TCAM use on the management of non-communicable diseases in these populations, this study examines the prevalence and characteristics of TCAM use for hypertension, its determinants, and its association with hypertension management outcomes and wellbeing among low-income adults in two Southeast Asian countries at different levels of economic and health system development, Malaysia and the Philippines. METHODS: We analysed cross-sectional data from 946 randomly selected adults diagnosed with hypertension from low-income rural and urban communities in Malaysia (n = 495) and the Philippines (n = 451). We compared the prevalence, characteristics and household expenditure on TCAM use between countries and used multi-level, mixed-effects regression to estimate associations between TCAM use and its determinants, and five hypertension management outcomes and wellbeing. RESULTS: The prevalence of TCAM use to manage hypertension was higher in the Philippines than in Malaysia (18.8% vs 8.8%, p < 0.001). Biologically-based modalities, e.g. herbal remedies, were the most common type of TCAM used in both countries, mainly as a complement, rather than an alternative to conventional treatment. Households allocated around 10% of health spending to TCAM in both countries. Belief that TCAM is effective for hypertension was a positive predictor of TCAM use, while belief in conventional medicine was a negative predictor. TCAM use was not strongly associated with current use of medications for hypertension, self-reported medication adherence, blood pressure level and control, or wellbeing in either country. CONCLUSIONS: A small, but significant, proportion of individuals living in low-income communities in Malaysia and the Philippines use TCAM to manage their hypertension, despite a general lack of evidence on efficacy and safety of commonly used TCAM modalities. Recognising that their patients may be using TCAM to manage hypertension will enable health care providers to deliver safer, more patient-centred care.