This article describes the knowledge, attitudes, and practice of in-patient physiotherapists in Ontario regarding the treatment of patients who are super-morbidly obese (SMO; i.e., those whose BMI is >50). A 62-item questionnaire was developed to assess demographics, sources of knowledge, current practice, and attitudes such as confidence, willingness, and the perceived effectiveness of treatment. It was distributed electronically using FluidSurveys. All physiotherapists working in a clinical role with adults in an in-patient setting in Ontario were eligible to participate. A total of 276 physiotherapists completed the survey. Most of them had learned about the treatment from non-structured sources such as clinical experience. More than half (52%) of the participants disagreed that their place of employment was well prepared to facilitate the treatment of patients who are SMO. The majority of respondents were confident in treating these patients, were willing to treat them (82%), and believed that physiotherapy would improve at least one health outcome (96%) for them; however, 46% were reluctant to treat for fear of personal injury. Participants most commonly felt limited by lack of equipment and lack of staff to assist. Physiotherapists have positive attitudes toward treating patients who are SMO, and increased equipment and staff to assist, as well as appropriate education, may decrease the fear of injury for physiotherapists while treating these patients and improve health outcomes for them.