The burden of hypertension is increasing worldwide, with higher rates in Low- and Middle-Income Countries (LMICs), like Nepal. Despite the availability of effective interventions, uncontrolled blood pressure remains a major challenge contributing to significant morbidity and mortality. Nonadherence to treatment and improper understanding of reasons for poor adherence are attributed to this phenomenon. It is widely understood that LMICs are impacted by financial pressures and a health workforce shortage to tackle these problems. Mobile phone uptake is high in LMICs and provides an opportunity to deliver tailored messages to improve medication adherence and contribute to blood pressure control. We aimed to develop and evaluate the feasibility of a text messaging mHealth intervention to improve blood pressure control among patients with hypertension in Nepal. We performed our research in two phases. In Phase I, a formative qualitative study (using a theoretical approach) was conducted to understand the barriers and facilitators for blood pressure control among patients with hypertension This study provided detailed insight into individual barriers to blood pressure control, such as low literacy of hypertension, non-adherence to treatment, and system-level barriers such as poor communication between providers and patients. In addition, we explored stigma and non-disclosure issues and social-cultural barriers attached to behaviour modification in this setting. The second part of this formative study reported the high potential of mHealth intervention in the study setting. Informed by the qualitative study, we co-designed a text messaging intervention (TEXT4BP) as part of Phase II. The feasibility of the TEXT4BP intervention was tested using a pilot randomised control trial study design. The TEXT4BP intervention was effective (p<0.001) in reducing systolic and diastolic blood pressure, improving blood pressure control and medication adherence among the intervention group when compared to the control group receiving usual care. In addition, the TEXT4BP intervention was found to be feasible and acceptable in the study setting. Our research has generated novel evidence on the co-design process of a mHealth intervention and demonstrated the effectiveness and acceptability of the intervention for hypertension management. The findings will inform further large-scale mHealth research and contribute to clinical practice with evidence-based adherence guidelines in Nepal.