Antibiotic resistance is increasing worldwide. The implementation of antibiotic stewardship programmes (ASPs) is of utmost importance to optimize antibiotic use in order to prevent resistance development without harming patients. The emergency department (ED), cornerstone between hospital and community, represents a crucial setting for addressing ASP implementation; however, evidence data on ASP in ED are poor. In this study, a 4-year, non-restrictive, multi-faceted ASP was implemented in a general ED with the aim to evaluate its impact on antibiotic use and costs. Secondly, the study focused on assessing the impact on length of hospital stay (LOS), Clostridioides difficile infection (CDI) incidence rate, and mortality in the patients' group admitted from ED to medical wards. The ASP implementation was associated with a reduction of antibiotic use and costs. A mild but sustained LOS decrease in all medical wards and a significant downward trend of CDI incidence rate were observed, while mortality did not significantly change. In conclusion, the implementation of our ED-based ASP has demonstrated to be feasible and safe and might clinically benefit the hospital admitted patients' group. Further research is needed to identify the most suitable ASP design for ED and the key outcome measures to reliably assess its effectiveness.