Background Exercise protects against somatic comorbidities and positively affects cognitive function and psychiatric symptoms in patients with severe mental illness. In forensic psychiatry, exercise is a novel concept. Staff at inpatient care facilities may be important resources for successful intervention. Little is known about staff’s knowledge, attitudes and behaviors regarding exercise in forensic psychiatric care. Aims To translate, culturally adapt and test the feasibility of the Exercise in Mental Health Questionnaire-Health Professionals Version (EMIQ-HP) in the Swedish context, and to use this EMIQ-HP-Swedish version to describe staff’s knowledge, attitudes and behaviors regarding exercise. Method The EMIQ-HP was translated, culturally adapted, pilot-tested and thereafter used in a cross-sectional nationwide survey. Results Ten of 25 clinics and 239 health professionals (50.1%) participated. Two parts of the EMIQ-HP-Swedish version showed problems. Most participants considered exercise to be a low-risk treatment (92.4%) that is beneficial (99.2%). Training in exercise prescription was reported by 16.3%. Half of participants (52.7%) prescribed exercise and 50.0% of those undertook formal assessments prior to prescribing. Conclusions Creation of the EMIQ-HP-Swedish version was successful, despite some clarity problems. Exercise appears to be prescribed informally by non-experts in Swedish forensic psychiatric care and does not address treatment goals.