Cancer patients face a heightened risk of infectious complications as a consequence of immunosuppression, chemotherapy-induced toxicities, hematopoietic dysfunction, and disruption of host physiology. In oncology, infections remain a leading cause of morbidity and mortality, underscoring the need to integrate insights from cancer immunology with evidence-based clinical pharmacotherapy. Challenges such as febrile neutropenia, antimicrobial resistance, and the safe use of antifungal and antiviral therapy require careful consideration of drug–drug interactions and therapeutic complexities. This Collection highlights multidisciplinary strategies that bridge physiology, infection biology, and precision medicine, with the goal of optimizing outcomes for patients vulnerable to infectious risks during cancer care.