Objective: As management for osteoarthritis, clinical practice guidelines (CPGs) have been published worldwide with the aim of attaining optimal treatment and rehabilitation. However, we suspect a lack of knowledge of and/or adherence to osteoarthritis CPGs in physiotherapists' clinical practice. There may be an evidence‐to‐practice gap in knee osteoarthritis rehabilitation among Japanese physiotherapists. Therefore, we aimed to measure the level of knowledge and adherence to osteoarthritis CPGs within a cohort of Japanese physiotherapists. Methods: An online survey was created based on three appropriate and high‐quality CPGs. The first two sections comprised 23 statements, and participants responded via a five‐point Likert scale ("completely disagree" to "completely agree"). Consensus was defined as ≥70% agreement with a statement. In the second section, participants read clinical scenarios and selected what they considered to be the most appropriate management and interventions. Results: The survey was completed by 558 Japanese physiotherapists. The mean age of the participants included in the analysis was 34.8 years, 61 participants were female (13.7%). Consensus was attained in just 12 out of 23 items (52%). In the second section, none of the physiotherapists were considered to have good knowledge of CPGs, 85.2% were considered to have only partial knowledge, and 14.8% had no knowledge. Familiarity with the CPGs was therefore poor and there was clearly poor adherence to the recommended rehabilitation guidelines. Conclusions: The level of knowledge and adherence to osteoarthritis CPGs within our cohort was poor, suggesting an evidence‐to‐practice gap in rehabilitation for knee osteoarthritis among Japanese physiotherapists. [ABSTRACT FROM AUTHOR]