Objectives: Readmission rates are a routinely used measure of patient and service outcomes, potentially improved by discharge planning. This pilot study aimed to develop a discharge checklist for psychiatric inpatients, exploring its feasibility, applicability, and impact on readmission rates. Methods: The study used a quasi-experimental, pre–post intervention design. The checklist was designed from an evidence-based literature review, and introduced for a three-month period, comparing 28-day readmission rates with the previous three months using interrupted time series analysis. Results: Checklists were completed for 80% of patients in the trial period, with 100% completion of checklist items. Demographic and clinical details for pre- and post-intervention groups were closely aligned. There was a small, but statistically non-significant, reduction in readmission rates. Conclusions: There was a high rate of checklist completion. The lack of significant reductions in readmission rates supports more development of the checklist application and design before a longer implementation period and re-evaluation.