Background: Individuals with serious mental illness (SMI) die 10–25 years earlier than the general population, partially due to cardiovascular disease. Those with SMI have poor cardiovascular disease behavioral risk profiles, including low physical activity engagement. This study examined the feasibility of providing city bike-share access to individuals with SMI. Methods: Participants were outpatients with SMI in a psychiatric rehabilitation program and were provided with a complimentary bike-share program membership (Nice Ride). Demographic and clinical variables were extracted from medical records. Lab values, body mass index, 10-year cardiovascular disease risk score, and tobacco use were collected at intake. Nice Ride provided ride frequency and duration data. Results: Of 22 SMI patients enrolled, 72.7% completed ≥1 ride. Among users, median ride length was 9 minutes (interquartile range = 49.5) and 56.3% averaged ≥10 minutes of riding per week. Individuals living <0.5 miles from a station were more likely to be users. Riding ≥10 minutes per week was associated with lower body mass index and male gender. Conclusion: Further work is warranted to determine if bike-share programs offer a feasible, scalable, and cost-effective method for increasing physical activity in those with SMI. These findings are currently being used for program adaptation to increase uptake.