Insomnia is a prevalent and distressing symptom among cancer patients, adversely impacting quality of life (QOL). Factors such as treatment-related side effects, diagnosis-related stress, and coexisting conditions, including anxiety and depression, often exacerbate insomnia. In Oman, the prevalence and contributing factors of insomnia in cancer patients remain underexplored. Additionally, despite the well-documented impact of insomnia on cancer prognosis, sleep education remains an underutilized component of oncology care. This study is aimed at determining the prevalence of insomnia among Omani cancer patients receiving chemotherapy and at identifying associated factors, emphasizing the need for structured sleep education as an essential part of cancer supportive care. A cross-sectional study was conducted from October 2022 to March 2023 at the Sultan Qaboos Comprehensive Cancer Care and Research Centre in Muscat, Oman. Adult Omani cancer patients undergoing chemotherapy during the study period were recruited. Data were collected using Arabic versions of the Pittsburgh Sleep Quality Index (PSQI) and Edmonton Symptom Assessment System-Revised (ESAS-r). A total of 211 patients participated (response rate 85.1%). Most were female (65.9%), married (83.9%), and had stage IV cancer (55.0%). The mean age was 49.6 +/- 11.7 years (range 19-81 years). Symptom burden, ranging from mild to severe, was reported by 30.8% of patients based on ESAS-r scores. Insomnia (PSQI score > 5) was identified in 55.0% of participants, with 34.1% reporting sleep disturbances after their diagnosis but prior to the initiation of chemotherapy. Insomnia was associated with pre-diagnosis sleeping problems (odds ratio (OR) = 3.04, p = 0.009), post-diagnosis but pre-chemotherapy sleep problems (OR = 7.34, p < 0.001), a history of smoking (OR = 4.00, p = 0.043), and symptom burden (OR = 3.78, p < 0.001). Multivariate analysis revealed that post-diagnosis/pre-chemotherapy sleep disturbances (OR = 4.09, p = 0.002) and symptom burden (OR = 3.02, p = 0.008) significantly increased the likelihood of insomnia. Insomnia is highly prevalent among Omani cancer patients undergoing chemotherapy, driven by high symptom burden and pre-existing sleep disturbances. Routine sleep assessments should be integrated into oncology care to identify at-risk patients and facilitate early intervention, ultimately improving sleep quality and enhancing QOL. Integrating structured sleep education into oncology training is crucial for effective cancer care. Approaches like CBT-I, digital tools, and hospital workshops equip providers and patients to manage sleep disturbances. Interprofessional education (IPE) boosts provider confidence, enhancing patient outcomes. Future efforts should focus on culturally tailored, evidence-based programs to support symptom management, treatment adherence, and survivorship.