Hematopoietic stem cell transplantation is one of the most clinically and pharmacotherapeutically complex healthcare processes. The introduction of new therapeutic strategies, improved survival, and the development of outpatient and home-based transplantation have transformed the care needs of these patients and expanded the role of hospital pharmacists within the multidisciplinary team. This article examines the transformation of pharmaceutical care in hematopoietic stem cell transplantation and integrates the available evidence and recommendations from leading scientific societies to propose a conceptual model of longitudinal pharmaceutical care, oriented toward clinical practice and adapted to patients' changing needs throughout the entire care pathway. It describes the evolution of the pharmacist's role, pharmaceutical care interventions across the different phases of transplantation, and the competencies required to address current challenges. In addition, the principles of capability, motivation, and opportunity are incorporated as a framework for individualizing follow-up and facilitating continuous and integrated care. The transition toward value-based pharmaceutical care requires complementing traditional activity indicators with the assessment of clinical outcomes, safety, efficiency, and patient experience. Precision dosing, pharmacogenomics, digital health, and artificial intelligence offer new opportunities to personalize interventions and support clinical decision-making, although their implementation should be accompanied by an assessment of their impact on health outcomes. The integration of these elements provides a structured view of pharmaceutical care in hematopoietic stem cell transplantation and a foundation for implementing and evaluating longitudinal care models that strengthen the pharmacist's contribution to the multidisciplinary team.