Aim: To investigate feasibility and acceptability of positive psychotherapy for acute psychiatric ward patients and staff, when delivered by non-psychology clinical staff, and co-produced with staff with lived experience. Method: Group or individual strengths-based positive psychotherapy was led by an activity coordinator and co-facilitated by a peer support worker with lived experience of mental health problems. It was delivered for acute ward patients and staff. Feasibility was measured by completion of session components and percentage of participants able to identify a strength, plan a strength-based activity, and activity completion. Acceptability was measured by comparing pre- and post-session mood, and with helpfulness ratings and narrative feedback. Results: Participants (n = 22) included 12 patients and 10 staff members. Participants were mainly female and of white or mixed ethnicity. Most patients had a psychotic disorder. Staff were nurses and healthcare assistants. The most identified strengths were self-regulation, social intelligence and perseverance. Typical activities included activity-scheduling, sleep hygiene, walking, gardening and cooking. High completion rates for components and activities indicated feasibility. Lack of adverse effect on mood, high helpfulness ratings, and positive feedback indicated acceptability. Conclusion: This evaluation indicates that non-psychology staff can deliver psychological interventions, that interventions can be co-produced with staff with lived experience, and that patient and staff participants can collaborate on these interventions. This shows how psychological interventions on acute wards can be inclusive, positively impact on ward culture, and be more widely delivered to support patients and staff.