Background: Prior research has shown preliminary evidence that calligraphy activity improves various body functions and decreases severity of psychotic symptoms in individuals with schizophrenia. However, major limitations of earlier studies include small and heterogeneous samples. The current large-scale randomized controlled trial examined effects of calligraphy activity on cognition (including attention), emotions, psychotic symptoms, quality of life, and mood in people with schizophrenia. Methods: One-hundred-and-fifty patients with schizophrenia were randomly allocated to the treatment group (receiving calligraphy activity) or the control group (receiving general activity), both of which lasted for 24weeks (70 minutes per session; one session per week). Assessments were conducted at pretest, posttest, and three-month follow-up. The Montreal Cognitive Assessment, Chu's Attention Test, Depression, Anxiety, and Stress Scale, Positive and Negative Syndrome Scale, World Health Questionnaire on the Quality of Life-Brief Form, and Visual Analogue Scale were used. Results: Improved cognition and attention were found in both groups, although no group effects were shown. The treatment group appeared to show lower severity of positive symptoms at follow-up than posttest, whereas the control group appeared to show the opposite pattern. Improved mood was found in the treatment group. Conclusion: This study provides evidence regarding effects of calligraphy activity on increasing cognition and potentially decreasing severity of positive symptoms in patients with schizophrenia. Calligraphy activity can be incorporated in clinical occupational therapy and may be provided to supplement medication treatment.