Obesity is a public health concern for the population in general and for children with autism spectrum disorder (ASD) specifically. The purpose of this study was to understand relationships between sensory patterns, obesity, and physical activity engagement of children with ASD (N = 77) sampled from a specialized community-based swimming program. This retrospective correlational study analyzed program data. Results show that almost half (42.2%) of the children were overweight or obese, and sensory avoiding behaviors were related to higher body mass index (BMI). Children participated in few formal and informal physically active recreation activities. Sensory seeking behaviors were associated with increased participation in informal activities, and higher BMI was associated with less participation in both formal and informal activities. Practitioners should consider sensory processing patterns and BMI when developing community-based programs to promote physical activity of children with ASD.