This review aims to evaluate the effectiveness of mindfulness-based interventions in improving the mental health of parents of children with intellectual and developmental disabilities (IDDs), specifically focusing on outcomes such as parental stress, anxiety, depression, and parent-child relationships. A systematic search was conducted across multiple databases, including Web of Science, PubMed, Embase, and others, up to December 2024. Two reviewers independently screened studies, extracted data, and assessed bias risk using the Cochrane Risk of Bias tool. Studies involving parents of children with intellectual or developmental disabilities who received mindfulness-based interventions and reported psychological outcomes were included. The meta-analysis was conducted using Review Manager 5.4 software, with a random effects model applied. This systematic review included 15 studies (1124 participants), of which 14 were used for meta-analysis (1078 participants). The results indicate that mindfulness-based interventions reduced the stress levels [SMD = − 0.26, 95% CI (− 0.49, − 0.04)], depressive symptoms [SMD = − 0.37, 95% CI (− 0.66, − 0.08)], distress [SMD = − 0.26, 95% CI (− 0.43, − 0.09)] and anxiety symptoms[SMD = − 0.35, 95% CI (− 0.66, − 0.04)] of parents of children with IDDs, while also improving parent-child relationships [SMD = − 0.32, 95% CI (− 0.05, − 0.58)], although the effects were moderate. Subgroup analyses revealed that interventions lasting 8 weeks or more [SMD =− 0.41, 95% CI (−0.67, −0.14)] and those targeting only the parents [SMD = − 0.26, 95% CI (− 0.44, − 0.08)] showed some positive effects in improving parent-child relationships or parent stress. Mindfulness-based interventions appear to have a positive effect on improving the mental health of parents of children with IDDs. However, the evidence of their effectiveness in enhancing parental mindfulness remains inconclusive. Future studies should consider the key factors influencing intervention implementation and optimize the design of large-scale randomized controlled trials to systematically and comprehensively assess the effectiveness and applicability of mindfulness-based interventions.