Background: There is little data on the use of smartphone-based applications for medication adherence and risk-factor control for the secondary prevention of stroke in low-and-middle-income countries (LMIC). Aims: To determine whether a smartphone-based app improved medication adherence, risk-factor control, and provided health education to stroke survivors for lifestyle and behavioural modifications. Methods: An unblinded, single-centre randomized controlled double arm trial with 1:1 allocation among stroke survivors was performed in South India. The primary outcome was medication adherence, with co-primary outcomes of lifestyle and behavioural factors and control of vascular risk factors, at three and six months. Results: Among 351 stroke survivors screened, 209 were recruited. The mean (SD) age of the intervention(n=105) group was 60(12) years and that of the control (n=104) group was 60(10) years. The primary outcome, mean medication adherence significantly improved in the intervention group with a between group difference of 0.735(95% CI:0.419-1.050), p<0.001. Being in intervention group (OR=4.5; 95% CI:2.3-8.9), stroke recurrence (OR=3.3(95% CI:1.9-7.8), and regular physician visits (OR=2.1; 95% CI:1.0–4.4) were significant predictors of good medication adherence. Considering the co-primary outcomes, compared to the control group, participants in the intervention group had a greater improvement in self-reported healthy diet intake (p=0.003), intake of fruits (p=0.005), and were physically more active (p=0.001). At six months mean fasting blood sugar (p=0.005) and high-density lipoprotein cholesterol higher (p=0.024) in the intervention group. Conclusions: The use of a mobile app is an effective method to improve medication adherence and risk- factor control in stroke survivors, and is feasible in LMICs like India. Data access statement: Data used during the study are available from the corresponding author on request. Trial registration: The study is registered in Clinical Trial Registry of India (CTRI/2022/06/042980).