Background: Digital health interventions are effective for hypertension self-management, but a comparison of the effectiveness and implementation of the different modes is lacking. This study aimed to compare the effectiveness of short message service (SMS), smartphone application and website interventions on improving blood pressure in people with hypertension, and to report on their reach, uptake and feasibility. Methods: CINAHL, Cochrane Central, Embase, Medline and PsychInfo were searched on 25th May 2022 for randomised controlled trials (RCTs) published in English from 1st January 2009 that examined the effectiveness of digital health interventions on reducing blood pressure in adults with hypertension. Risk of Bias was assessed using Cochrane Risk of Bias 2 (RoB 2). Data on systolic and diastolic blood pressure reduction were synthesised in a meta-analysis, and data on reach, uptake and feasibility were summarised narratively. The level of evidence was evaluated using GRADE. Results: Of 3,235 records identified, 29 RCTs from 12 countries (n = 7,592 participants) were included. Eleven studies used SMS as the primary mode of delivery of the digital health intervention, 13 employed smartphone applications, and five implemented the interventions via websites. Overall, digital health intervention group participants achieved a -3.62 [-5.22, -2.02] mm Hg greater reduction in systolic blood pressure compared to control group participants. All three different modes of delivery of the intervention resulted in statistically significant reductions in systolic blood pressure compared to the control group, with no statistically significant differences between the three different modes of delivery (p = 0.73). Due to considerable heterogeneity between included studies and the high risk of bias overall, the level of evidence was assigned a low overall score. SMS intervention studies reported higher reach compared to smartphone application and website-based intervention studies, but smartphone application studies reported higher uptake compared to the other two. Conclusion: Digital health interventions were associated with improved blood pressure control, compared to usual care, regardless of the mode of delivery. Considering that at least 92% of the global population has access to a digital telecommunication medium and that numerous digital health tools are available for hypertension management, clinicians should familiarise themselves with this modality of program delivery and encourage people with hypertension to use evidence-based digital health tools for improving their self-management of hypertension. Digital health interventions now have the option of several modes of delivery and choice should be made based on context, feasibility, economics, and patients preference, emphasising the importance of study co-design.