Individuals diagnosed with severe mental illness have higher rates of obesity than the general population due to a range of factors, including: medication side effects, poor nutrition and reduced physical activity. Obesity is associated with increased mortality and reduced quality of life. Evidence suggests that lifestyle interventions can be effective in addressing this issue. While such interventions would appear to fit within the scope of practice of occupational therapy, there is no publication synthesising the existing literature regarding occupational therapy interventions addressing lifestyle factors associated with obesity. To determine what is known from the existing literature about occupational therapy interventions addressing weight gain and obesity in adults diagnosed with severe mental illness. A scoping review was conducted. Searches were performed in online databases, occupational therapy journals and grey literature databases. Thematic analysis occurred across all articles included in the review. A total of 14 articles were included in the review. Analysis revealed a central theme of supporting occupational performance and participation in health promoting occupations. This central theme consisted of four categories; facilitating client-centred practice, addressing personal performance issues, addressing environmental barriers and providing the 'just right' challenge. These findings suggest occupational therapists are providing occupation focused interventions that are aligned with current clinical guidelines. However, more research is required to strengthen evidence-based occupational therapy practice in this important area.