Background: The review aimed to investigate the effectiveness of parent-child relationship interventions for families of children with intellectual disability up to 12 years old. Methods: Quasi-experimental or randomised controlled trials (RCTs) of interventions targeting the parent-child relationship where =50% of children had an intellectual disability were included. Meta-analyses of parent-child relationship outcomes and child outcomes used standardised mean difference as the effect size. Results: Twenty-seven papers were included (N = 1325). Parent-child relationship outcomes improved significantly (n = 1325; g = 1.08, 95% CI: 0.64, 1.52) with a large effect size that was robust to sensitivity analyses. Child developmental outcomes improved significantly (n = 1082; g = 0.65, 95% CI: 0.23, 1.07), and indicated a large effect size for child socialisation and communication. Conclusions: Findings suggest that interventions targeting parent-child relationship quality are associated with substantial improvements in parent-child relationship and may improve child outcomes related to socialisation and communication.