BACKGROUND: Considering the persistent nature and higher prevalence of insomnia in cancer patients and survivors compared with the general population, there is a need for effective management strategies. This systematic review and meta-analysis aimed to comprehensively evaluate the available evidence for the efficacy of pharmacological and nonpharmacological interventions for insomnia in adult cancer patients and survivors. METHODS: Following the PRISMA guidelines, we analyzed data from 61 randomized controlled trials involving 6528 participants. Interventions included pharmacological, physical, and psychological treatments, with a focus on insomnia severity and secondary sleep and non-sleep outcomes. Frequentist and Bayesian analytical strategies were employed for data synthesis and interpretation. RESULTS: Cognitive-Behavioral Therapy for Insomnia (CBT-I) emerged as the most efficacious intervention for reducing insomnia severity in cancer survivors and further demonstrated significant improvements in fatigue, depressive symptoms, and anxiety. CBT-I showed a large postintervention effect (g = 0.86; 95% confidence interval [CI] = 0.57 to 1.15) and a medium effect at follow-up (g = 0.55; 95% CI = 0.18 to 0.92). Other interventions such as bright white light therapy, sleep medication, melatonin, exercise, mind-body therapies, and mindfulness-based therapies showed benefits, but the evidence for their efficacy was less convincing compared with CBT-I. Brief Behavioral Therapy for Insomnia showed promise as a less burdensome alternative for patients in active cancer treatment. CONCLUSIONS: CBT-I is supported as a first-line treatment for insomnia in cancer survivors, with significant benefits observed across sleep and non-sleep outcomes. The findings also highlight the potential of less intensive alternatives. The research contributes valuable insights for clinical practice and underscores the need for further exploration into the complexities of sleep disturbances in cancer patients and survivors.