Background <p>Respiratory syncytial virus (RSV) infection is a leading cause of hospitalization among infants and young children. Broad immunization with the monoclonal antibody nirsevimab represents a promising preventive strategy. However, real-world data on its impact at the population level remain limited, particularly in routine clinical settings.</p> Methods <p>This retrospective single-center study evaluated a cohort of 261 children under two years of age hospitalized with RSV across three seasons (2018–2019, 2023–2024, 2024–2025) at a Berlin tertiary care hospital.</p> Results <p>We analyzed admissions and clinical courses of RSV-associated hospitalizations in children &lt; 2 years of age at a large tertiary care center in Germany between 2018 and 2025. Following the nationwide introduction of nirsevimab in 2024, the number of RSV-related hospitalizations in our center decreased by 51% compared to the previous season. During the 2024/2025 season 90.2% of hospitalized patients had not received nirsevimab immunization.</p> Conclusion <p>The introduction of nirsevimab was associated with a substantial reduction in RSV-related hospitalizations in infants and young children in a real-world clinical setting. These findings support a beneficial role of passive immunization with nirsevimab and highlight its potential to reduce RSV-related disease burden.</p>