Background: Limited evidence suggests that physical activity has beneficial effects in people with inflammatory bowel disease (IBD). This study aimed to determine the physical activity habits of adults with IBD, the limitations to physical activity they experience because of their disease, and the extent to which their physical activity is affected by various demographic, clinical, and psychological factors. Methods: Data were collected on 859 adult participants (52% with Crohn's disease, 75% women) through an online survey conducted between May and June 2016. Measures included physical activity (International Physical Activity Questionnaire), psychological symptoms (Hospital Anxiety and Depression Scale), fatigue (subitems of IBD fatigue scale), exercise perceptions (Exercise Benefits/Barriers Scale), and disease activity. Regression analyses were used to identify predictors of physical activity. Results: Only 17% of respondents were categorized as "high active." Self-reported physical activity levels decreased, and fatigue and psychological scores increased, with increasing disease activity. Walking was the most common activity performed (57% of respondents) and running/jogging the most commonly avoided (34%). Many participants (n = 677) reported that IBD limited their physical activity, for reasons including abdominal/joint pain (70%), fatigue/tiredness (69%), disease flare-up (63%), and increased toilet urgency (61%). Physical activity was independently associated with depression, disease activity, and perceived barriers to exercise in people with Crohn's disease, and depression and age in people with ulcerative or indeterminate colitis (all P <= 0.038). Conclusions: This survey highlights several important factors that should be considered by designers of future physical activity interventions for people with IBD.