Background <p>Nurses’ core competency in intravenous (IV) therapy directly impacts patient safety and treatment outcomes. This study aimed to identify latent classes of nurses’ core competency in IV therapy using latent profile analysis and explore key factors influencing these classes to inform targeted interventions.</p> Methods <p>A multicenter cross-sectional study was conducted from October 2023 to January 2024, involving 821 clinical nurses from 20 provincial-level regions in China. Data was collected using the validated Core Competency in Intravenous Therapy Scale. Latent profile analysis was used to identify competency classes, and multivariate logistic regression was performed to explore risk factors.</p> Results <p>Three distinct latent classes were identified: ‘Low IV-Core Competency’ (41.3%), ‘Moderate IV-Core Competency’ (45.9%), and ‘High IV-Core Competency’ (12.8%). Multivariate logistic regression showed that non-specialist nurses in IV therapy and non-participation in intravenous therapy training programs were strongly associated with lower competency.</p> Conclusions <p>There is a critical need to improve IV therapy core competency among clinical nurses. Investments in IV specialist nurse development and standardized training are essential to enhance therapy quality and patient safety.</p> Trial registration <p>Not applicable.</p>