Abstract Background Typically, specialist mental health professionals deliver psychological interventions for individuals with poorly controlled type 2 diabetes mellitus (T2DM) and related mental health problems. However, such interventions are not generalizable to low- and middle-income countries, due to the dearth of trained mental health professionals. Individuals with little or no experience in the field of mental health (referred to as non-specialists) may have an important role to play in bridging this treatment gap. Aim To synthesise evidence for the effectiveness of non-specialist delivered psychological interventions on glycaemic control and mental health problems in people with T2DM. Methods Eight databases and reference lists of previous reviews were systematically searched for randomized controlled trials (RCTs). Outcome measures were glycated hemoglobin (HbA1c), diabetes distress and depression. The Cochrane Collaboration Risk of Bias Tool was used for risk of bias assessment. Data from the included studies were synthesized using narrative synthesis and random effects meta-analysis. Results 16 RCTs were eligible for inclusion in the systematic review. The 11 studies that were pooled in the meta-analysis demonstrated a reduction in HbA1c in favor of non-specialist delivered psychological interventions when compared with control groups (pooled mean difference = − 0.13; 95% CI − 0.22 to − 0.04, p = 0.005) with high heterogeneity across studies (I² = 71%, p = 0.0002). The beneficial effects of the interventions on diabetes distress and depression were not consistent across the different trials. Conclusion Non-specialist delivered psychological interventions may be effective in improving HbA1c. These interventions have some promising benefits on diabetes distress and depression, although the findings are inconclusive. More studies of non-specialist delivered psychological interventions are needed in low- and middle-income countries to provide more evidence of the potential effectiveness of these interventions for individuals living with T2DM.