Despite the physical, cognitive, and psychological health benefits associated with moderate to vigorous physical activity (MVPA), children with behavioral health disorders such as attention deficit/hyperactivity disorder, autism, and oppositional defiant disorder tend to display very low levels of MVPA. Given that community physical activity programs generally do not cater to children with behavioral health disorders, special education and therapeutic school settings are particularly important environments in which to test MVPA programs in this underserved population. Manville Moves is a 7-wk cybercycling intervention designed specifically for children with behavioral health disorders, including social, emotional, and behavioral disabilities. The program was integrated into school physical education (PE) programming in a therapeutic day school and evaluated over one school year. Guided by Carroll et al.'s framework of implementation fidelity, this mixed methods study documents the implementation fidelity of, including student engagement in, Manville Moves. Manville Moves was implemented with high fidelity and engaged all enrolled children (N = 103). Nearly 90% of sessions were implemented as planned. Students met almost all riding intensity and duration targets; participants averaged 100.5 min of riding and 76% of maximum HR over the course of the intervention. Staff reported low levels of burden, and student refusals were extremely rare. In addition, most students demonstrated high levels of engagement, with the awards, prizes, and video gaming mode all identified as critical motivators. In conclusion, beyond demonstrating that a cybercycling PE curriculum is feasible and can engage students with behavioral health challenges, this study identified several lessons learned that could benefit future implementations of the program.