The aims were (i) to determine the effects of Cognitive behavioral therapy for insomnia (CBT-I) on sleep disturbances, pain intensity and disability in patients with chronic musculoskeletal pain (CMP), and (ii) to determine the dose-response association between CBT-I dose (total minutes) and improvements in sleep disorders, pain intensity and disability in patients with CMP. A comprehensive search was conducted in PubMed/MEDLINE, Web of Science, CINAHL, and SCOPUS until December 17, 2023. Randomized clinical trials (RCTs) using CBT-I without co-interventions in people with CMP and sleep disorders were eligible. Two reviewers independently extracted data and assessed risk of bias and certainty of the evidence. A random effects meta-analysis was applied to determine the effects on the variables of interest. The dose-response association was assessed using a restricted cubic spline model. Eleven RCTs (n = 1801 participants) were included. We found a significant effect in favor of CBT-I for insomnia (SMD: −1.34; 95%CI: −2.12 to −0.56), with a peak effect size at 450 min of CBT-I (−1.65, 95%CI: −1.89 to −1.40). A non-significant effect was found for pain intensity. A meta-analysis of disability was not possible due to the lack of data. This review found benefits of CBT-I for insomnia compared to control interventions, with a large effect size. In addition, it was estimated that a 250-min dose of CBT-I had a large effect on reducing insomnia and that the peak effect was reached at 450 min. These novel findings may guide clinicians in optimizing the use of CBT-I in people with CMP and insomnia.