Background: Drug-related problems (DRPs) are frequent among cancer patients and can have a poor influence on the quality of life (QoL), and increase morbidity as well as mortality. Aim of the work: This study aimed to assess the impact of clinical pharmacist-implemented prescriber's education on the prevalence of DRPs and patients' QoL. Patients and Methods: A cross-sectional, 3 phases interventional study (pre-education phase, education phase, and post-education phase) was conducted between May 2018 and May 2020. Prescriptions and filled QoL questionnaires were collected for 500 patients in pre-education and 500 patients' post-education phases from Cairo University National Cancer Institute (Cairo, Egypt) and Assiut University Hospital (Assiut, Egypt). The QoL for each patient was assessed using the Arabic version of the European Organization for Research and Treatment of Cancer (EORTC) QLQ C30 QoL questionnaire. Results: Following clinical pharmacist education, the total number of DRPs in the post-education phase significantly decreased by 43.14 % (p < 0.0001) compared to the pre-education phase. The acceptance rate of prescribers was 88.6% to the recommendations done by the clinical pharmacist. Comparing EORTC QLQ C30 questionnaire scores in pre- and post-education phases, there was a statistically significant improvement with fewer problematic patients in the global health status, functional, and symptom scales in the post-education phase. Conclusion: Pharmacist interventions can potentially minimize the incidence of DRPs and are associated with improvement of QoL scores which highlights the importance of the clinical pharmacist's role in cancer care.