Purpose: Among cancer survivors, physical activity (PA) is associated with reductions in cancer recurrence, morbidity, and mortality. Most young adult (YA) survivors do not attain adequate PA. Digital modalities, specifically wearable activity monitors with a paired mobile application and private social media group for support offer a promising approach for promoting PA among YAs. We conducted a pilot randomized controlled trial of this intervention. To evaluate its acceptability and perceptions of the intervention components, we conducted qualitative interviews with those in the intervention. The results of our interviews serve to refine future interventions to better serve this population. Methods: Semistructured qualitative interviews with 13 YA cancer survivors ages 20-39 who participated in the intervention assessed perceptions of the digital components of the study and buddy system of nominating a friend to participate in PA with the survivor. Analyses included a qualitative thematic analysis of the interview transcripts and coded interview segments into three predetermined categories: facilitators, limitations, and suggestions. Results: Participants described wide-ranging benefits of the intervention, citing the Fitbit device and buddy system as major motivators to engage in PA and reach goals. Most participants noted feelings of increased physical and emotional wellness. The most-cited limitation of the intervention was the automated text messages, which participants found impersonal. Suggestions for improvement included integrating more elements of competition and group challenges. Conclusion: This digital PA intervention was perceived as feasible and acceptable to YA cancer survivors and appears promising for promoting PA and improving long-term health and quality of life. Clinicaltrial.gov identifier number: NCT03233581; Date of registration: July 28, 2017.