Caregivers of children undergoing allogeneic hematopoietic stem cell transplantation (HSCT) face substantial psychological, social, and logistical challenges throughout the transplant journey. This multicenter, longitudinal qualitative study explored the evolving mental health experiences, stressors, and coping strategies of 49 caregivers interviewed across four key time points: transplant (d 0), d +30, d +100, and d +180. Participants reported acute distress early in the process, exacerbated by restrictive hospital environments, the demands of hypervigilant caregiving, financial strain, and the emotional toll of family separation. As care transitioned to the outpatient setting, challenges shifted toward navigating complex home care, managing lingering uncertainty, and balancing the needs of other family members. Throughout the process, caregivers expressed heightened anxiety related to fear of relapse, infection, and long-term complications. Despite these burdens, many caregivers described powerful sources of resilience. Children's emotional strength, honest communication, and a desire to return to normal life helped sustain caregiver optimism. Support from the healthcare team, financial assistance, and access to professional mental health services further alleviated stress. Caregivers emphasized the need for enhanced inpatient environments, clearer outpatient guidance, structured mental health resources, and practical tools like caregiver handbooks. These findings underscore the need for holistic, family-centered care that addresses caregiving's psychological and practical dimensions during pediatric HSCT. Tailored, time-sensitive support strategies are essential to improving caregiver well-being and, in turn, optimizing patient outcomes across the transplant continuum.