BackgroundThere is a lack of research on the relationship between pain catastrophizing, kinesiophobia, and physical activity (PA) in people with haemophilia (PWH), and the underlying mechanisms connecting these variables remain unclear.AimThe study's aim was to clarify the roles of kinesiophobia and self‐efficacy in the relationship between pain catastrophizing and PA in PWH.MethodsThis cross‐sectional study included adult PWH at the Haemophilia Centre of a Tertiary hospital in Beijing, China. The following questionnaires were used to collect data: the general information, the International Physical Activity Short Questionnaire, the Pain Catastrophizing Scale, the Tampa Scale of Kinesiophobia Scale, and the Exercise Self‐Efficacy Scale.ResultsThe study included a total of 187 PWH, including 154 having haemophilia A and 33 having haemophilia B. The median interquartile range of PA was 594 (198, 1554) MET‐min/wk. There were significant differences in PA of patients based on age stage, treatment modality, highest pain score within the last seven days, and presence of haemophilic arthropathy (p < .05). It was showed that pain catastrophizing could directly predict PA (p < .001), accounting for 38.13% of the total effect. Pain catastrophizing also had indirect effects on PA through the mediating factors of kinesiophobia or self‐efficacy, and through the chain‐mediating effect of kinesiophobia and self‐efficacy, accounting for 38.40%, 17.07%, and 6.40%, respectively.ConclusionThe study discovered that PWH have limited PA due to pain catastrophizing. This not only directly affects their activity but also indirectly influences it through kinesiophobia and self‐efficacy.