The beneficial effect of implementation intentions (II) on prospective memory (PM) deficits in patients with schizophrenia has been reported. However, these studies were limited to brief interventions such that the transfer and long-term effects of II training remains unclear. This study examined whether a 10-session II programme could improve PM performance, social functioning and functional capacity in patients with schizophrenia immediately after training and at 3-month follow-up. Patients with schizophrenia (n = 42) recruited from the community were randomly assigned to II training (n = 21) or treatment as usual (TAU) (n = 21). Participants in the II group learned the verbal and imagery component of II and were encouraged to apply these strategies in their daily lives. We found that the II group performed better than the TAU group on computer-based PM tasks and a daily life PM task (telephone call at specified date and time) at post-treatment and at 3-month follow-up. The II group also exhibited better working ability than the TAU group at post-treatment. Our results suggest that the II intervention programme may have lasting beneficial effects in PM performance and significant transfer effects to functional capacity in schizophrenia patients.