Background: Collaboration between parents and school nurses is important for effective healthcare in schools. This study focuses on the competency of school nurses, which encompasses their knowledge and self-efficacy in diabetes care, and investigates how these factors, along with workload, influence healthcare partnerships in schools. However, it is unknown whether school nurses' knowledge and self-efficacy about diabetes care, as well as their workload, affect school healthcare partnerships concerning children with type 1 diabetes. Aim: This study aimed to investigate the impact of school nurses' self-efficacy, knowledge, attitude, and role overload on healthcare partnerships with parents of children with type 1 diabetes in schools. Design: A cross-sectional, descriptive design. Setting and participants: Between December 2023 and January 2024 in South Korea, 142 elementary- and middle- school nurses participated in this study. Methods: School healthcare partnership, self-efficacy in diabetes education, knowledge of and attitude toward school healthcare for type 1 diabetes, and the role-overload scale were utilized in the analysis. Data were analyzed using multiple regression. Results: Knowledge of school healthcare ((3 = 0.34, p < .001) and attitude toward it ((3 = 0.29 p = .001) for type 1 diabetes, as well as the grade level of the current employing school ((3 =-0.15, p = .039) were predictors of school healthcare partnerships. These three variables explained 30.3 % of the total variance in school healthcare partnerships (F = 21.44, p < .001). Conclusions: Knowledge of school healthcare and attitudes toward it for type 1 diabetes were identified as factors in school nurses' school healthcare partnerships. Therefore, interventions to strengthen school nurses' competencies should be developed to improve school healthcare partnerships.