Background: Hematopoietic stem cell transplantation (HCT), also referred to as blood and marrow transplantation (BMT), is a high-risk, but potentially curative therapy for a number of cancer and noncancer conditions. BMT Roadmap (Roadmap 1.0) is a mobile health app that was developed as a family caregiver-facing tool to provide informational needs about the health status of patients undergoing inpatient HCT.; Objective: This study explored the views and perceptions of family caregivers of patients undergoing HCT and their input regarding further technology development and expansion of BMT Roadmap into the outpatient setting (referred to as Roadmap 2.0).; Methods: Semistructured qualitative interviews were conducted among 24 family caregivers. Questions were developed from existing literature coupled with prior in-depth observations and interviews in hospital-based settings to explore the study objectives. Participants were recruited during routine outpatient clinic appointments of HCT patients, and all interviews were conducted in the participants' homes, the setting in which Roadmap 2.0 is intended for use. A thematic analysis was performed using a consistent set of codes derived from our prior research. New emerging codes were also included, and the coding structure was refined with iterative cycles of coding and data collection.; Results: Four major themes emerged through our qualitative analysis: (1) stress related to balancing caregiving duties; (2) learning and adapting to new routines (resilience); (3) balancing one's own needs with the patient's needs (insight); and (4) benefits of caregiving. When caregivers were further probed about their views on engagement with positive activity interventions (ie, pleasant activities that promote positive emotions and well-being such as expressing gratitude or engaging in activities that promote positive thoughts, emotions, and behaviors), they preferred a "menu" of positive activities to help support caregiver health and well-being.; Conclusions: This study involved family caregivers as participants in the development of new components for Roadmap 2.0. Our research provided a further understanding of the many priorities that hematopoietic stem cell transplant family caregivers face while maintaining balance in their lives. Their schedules can often be unpredictable, even more so once the patient is discharged from the hospital. Our findings suggest that expanding Roadmap 2.0 into the outpatient setting may provide critical caregiver support and that HCT caregivers are interested in and willing to engage in positive activities that may enhance well-being and attenuate the stress associated with caregiving.; International Registered Report Identifier (irrid): RR2-10.2196/resprot.4918