Background Poor management of type 2 diabetes mellitus may affect individuals’ physical and emotional health. Access to ongoing psychosocial interventions through technological platforms may potentially minimise diabetes complications and improve health-related outcomes. However, little is known about the effectiveness of such interventions on diabetes distress and health-related outcomes. Objective To synthesise the best available evidence concerning the effectiveness of technology-based psychosocial interventions on diabetes distress, self-efficacy, health-related quality of life, and HbA1c level in adults with type 2 diabetes mellitus. Methods A search of eleven databases was conducted to identify randomised controlled trials that examined the effects of technology-based psychosocial interventions on the outcomes. Randomised controlled trials reported in English from 2010 to 2020 were included. Selection of studies, quality appraisal, and data extraction were conducted by two reviewers independently. Meta-analyses, subgroup analyses and sensitivity analysis were performed using Review Manager. Intervention effects was measured using standardise mean difference. Results Twenty randomised controlled trials fulfilled the eligibility criteria and 18 randomised controlled trials were included in meta-analysis. technology-based psychosocial interventions improved diabetes distress, self-efficacy and HbA1c levels with significant and small effect sizes. Subgroup analyses revealed greater improvement in health-related quality of life for participants with comorbid depression and lower HbA1c levels for studies with lesser than 100 participants. Conclusion The findings of this review increase knowledge on the effectiveness of technology-based psychosocial interventions on diabetes distress and self-efficacy. However, evidence to support the effects of technology-based psychosocial interventions on HbA1c and health-related quality of life was not strong. More research is needed to examine the effectiveness of the psychosocial interventions delivered through mobile applications or virtual reality.