Targeting individuals' beliefs that they are able to eat healthily can improve dietary-related behaviours. However, the most effective behaviour change techniques (BCTs) to promote dietary self-efficacy have not been systematically reviewed. This research addressed this gap. Studies testing the effect of interventions on healthy eating and underlying dietary-related self-efficacy, within randomised controlled trials, were systematically reviewed in MEDLINE, EMBASE and PSYCINFO. Two reviewers independently coded intervention content in both intervention and comparison groups. Data pertaining to study quality were also extracted. Random effects meta-analysis was used to calculate an overall effect size on dietary self-efficacy for each study. The associations between 26 BCTs and self-efficacy effects were calculated using meta-regression. In some of the analyses, interventions that incorporated self-monitoring (tracking one's own food-related behaviour), provided feedback on performance, prompted review of behavioural goals, provided contingent rewards (rewarding diet success), or planned for social support/social change increased dietary self-efficacy significantly more than interventions that did not. Stress management was consistently associated with self-efficacy effects across all analyses. There was strong evidence for stress management and weaker evidence for a number of other BCTs. The findings can be used to develop more effective, theory- and evidence-based behavioural interventions.