(1) Background: Inadequate physical activity is an ongoing issue for pediatric survivors of childhood cancer and hematopoietic stem cell transplant (HSCT), increasing their risk for chronic health conditions and decreasing quality of life. Team Survivors is a 12-week program in which survivors train as a group to participate in a community triathlon. Preliminary findings from a quality improvement project of Team Survivors were used to assess its feasibility in influencing survivors’ physical activity and quality of life and their family’s perception of the program. (2) Methods: Repeated measures t-tests evaluated changes in caregiver-reported exercise self-efficacy and health-related quality of life (HRQoL). These findings were supplemented by a narrative review of qualitative data from caregivers and survivors on their overall experience and satisfaction with the program. (3) Results: All participants successfully completed the triathlon, and families reported satisfaction with the program’s logistics (i.e., coordination, coaching, and practice). Neither caregiver-reported exercise self-efficacy nor HRQoL significantly differed between pre- and post-intervention, but notable improvements were reported in all domains of HRQoL. Qualitatively, the perceived benefits reported by caregivers and survivors were multifaceted. Physical benefits included improvements in survivors’ physical activity level and endurance. Psychosocially, caregivers and survivors reported greater confidence and motivation for physical activity, improved coping, and increased social engagement and feelings of normalcy. (4) Conclusions: Mixed method results support the feasibility of Team Survivors in positively impacting survivors’ ability to engage in physical activity. The multifaceted structure of the program may more broadly impact psychosocial functioning in addition to physical activity. Future studies require a larger sample size to adequately power the analyses.