BACKGROUND: Physical activity helps cancer survivors ameliorate physiological and psychosocial effects of disease and treatments. However, few cancer survivors meet physical activity recommendations, with many facing barriers such as limited interest, enjoyment, and social support. It is critical to develop enjoyable and supportive physical activity programs to improve well-being among the growing population of cancer survivors. Pickleball is increasingly popular due to its unique combination of physical activity, friendly competition, and social interaction, making it a promising strategy to increase and sustain physical activity in cancer survivorship. OBJECTIVE: We examined feasibility, acceptability, and preliminary outcomes in a single-arm pilot study of Project Rally, a YMCA-based pickleball program for adult cancer survivors. RESULTS: Twenty-one cancer survivors and seven family or friend partners enrolled in Project Rally with a targeted program duration of 3-7 months. All programming and study assessments occurred at a single YMCA with coaching and supervision from a YMCA exercise trainer and certified pickleball coach. Feasibility and acceptability were strong and met a priori targets for recruitment, retention, intervention adherence, and ratings of program aspects. Participants demonstrated significant increases in physical activity and improvements in aspects of fitness, physical functioning, and social support. CONCLUSION: These results will inform further development of the Project Rally program to increase physical activity and improve cancer survivorship outcomes, including efforts to expand the program's scale and reach more survivors via community-based delivery.