Objective: Psychological distress has a high impact on quality of life in patients with multiple sclerosis (MS), Parkinson's disease (PD), and Huntington's disease (HD). Studies have shown that cognitive behavioral therapy (CBT) and mindfulness-based therapies (MBTs) are successful in reducing psychological distress in patients with anxiety, depressive, and chronic somatic disorders. We aimed to investigate the effectiveness of these therapies in MS, PD, and HD patients. Methods: We performed a comprehensive literature search in PubMed, PsycINFO, Embase and the Cochrane Central Register of Controlled Trials up to March 2018. Randomized controlled trials (RCTs) investigating a CBT or MBT and reporting psychological outcome measures were included. Two separate meta-analyses were performed; one on studies comparing psychological therapy with a treatment as usual or waitlist condition and one on studies with active treatment control conditions. Results: The first meta-analysis (N = 12 studies, 8 in MS and 4 in PD populations) showed a significant effect size of g = 0.51 in reducing psychological distress. The second meta-analysis (N = 7 studies, in MS populations) showed a mean effect size of g = 0.36. No RCTs were found in HD populations. The overall quality of the included studies was low and considerable heterogeneity was found. No evidence was found for publication bias. Conclusion: CBT and MBTs have a small to moderate effect on reducing psychological distress in patients with PD and MS. However, more research with better methodological quality and larger study samples is warranted, especially in HD patient populations.