Patient participation is a central concept in modern health care and an important factor in theories/models such as person‐centred care, shared decision‐making, human rights approaches, and recovery‐oriented practice. Forensic psychiatric care involves the treatment of patients with serious mental illnesses who also have committed a crime, and there are known challenges for mental health staff to create a health‐promoting climate. The aim of the present study was to describe mental health professionals' perceptions of the concept of patient participation in forensic psychiatric care. Interviews were conducted with 19 professionals and were analysed with a phenomenographic approach. The findings are presented as three descriptive categories comprising five conceptions in an hierarchic order: 1. create prerequisites – to have good communication and to involve the patient, 2. adapt to forensic psychiatric care conditions – to take professional responsibility and to assess the patient’s current ability, and 3. progress – to encourage the patient to become more independent. The findings highlight the need for professionals to create prerequisites for patient participation through good communication and involving the patient, whilst adapting to forensic psychiatric care conditions by taking professional responsibility, assessing the patient’s ability, and encouraging the patient to become more independent without adding any risks to the care process. By creating such prerequisites adapted to the forensic psychiatric care, it is more likely that the patients will participate in their care and take more own responsibility for it, which also may be helpful in the patient recovery process.