Advance care planning is recommended as part of standard medical services. Readiness, denoting stages of behavior change, exerts a substantial influence on its uptake. However, the characteristics and impacts of advance care planning interventions on readiness are not well-established. We systematically reviewed and conducted a meta-analysis of randomized controlled trials assessing the effects of advance care planning interventions on readiness. Studies were appraised using Joanna Briggs Institute Critical Appraisal tools. Meta-analyses were performed using mean difference of continuous variables or risk ratios of binary variables and their 95 % confidence interval as the pooled effect sizes. Eight studies were included in this review and were all rated low quality. Meta-analysis showed that interventions resulted in slight improvement in overall readiness (mean difference = 0.19, 95 % confidence interval: 0.02–0.36) for advance care planning. However, statistically significant effects of interventions were not identified for readiness in relation to specific behaviors (appointment of a healthcare proxy, talking to a healthcare proxy, talking to a medical practitioner about living wills, and signing a living will). Our meta-analyses demonstrated that interventions can improve the overall readiness for advance care planning, suggesting the necessity to integrate readiness into future health policies and clinical practices. Nevertheless, the absence of significant effects on specific behavioral readiness underscores the requirement for additional refinement in intervention design, advanced technologies, and theoretical foundations. Not registered.