IntroductionIn the COVID-19 environment of reduced patient interaction with the healthcare system, evidenced-based self-care of chronic disease is vital. We will evaluate the effect of an online chronic disease self-management programme (CDSMP) plus medication adherence tools on systolic blood pressure (SBP) (primary aim) and, seek to understand the barriers and facilitators to implementation of this modified CDSMP in faith-based organisations (FBOs) (secondary aim).MethodsWe will conduct an unblinded cluster randomised trial in FBOs throughout Barbados. Eligibility: Persons ages 35–70 years; a previous diagnosis of hypertension or currently on antihypertensive therapy and the occurrence of two or more blood pressure readings above 130 mm Hg (systolic) or 80 mm Hg (diastolic) on the day of recruitment. Persons not known to have hypertension but who have two or more blood pressure readings at or above 130 mm Hg (systolic) or 80 mm Hg (diastolic) on two recruitment days at least 1 week apart will also be eligible. The unit of randomisation is a church cluster which consists of 7–9 churches. We will perform block randomisation to assign 24 clusters to intervention or control. The intervention has three components: modified CDSMP workshops, distribution of medication pill boxes and use of social media (WhatsApp V.2.0) to encourage medication adherence. Controls will receive one didactic lecture only. We will determine the mean changes in SBP levels for the intervention group versus controls and compare differences in outcomes 6 months’ post intervention using mixed effects regression models.Ethics and disseminationThis project has received ethical approval from the Institutional Review Board of the University of the West Indies in Barbados. Dissemination will use peer-reviewed publications, policy briefs to government and guidelines to leaders of FBOs. We aim to increase the proportion of patients with controlled hypertension and inform implementation of self-management programmes in small populations.Trail registration numberNCT04437966