BACKGROUND: Enteral nutrition (EN) is essential for ICU patients, but EN-associated diarrhea (ENAD) affects 48.6-89.0% of them, increasing complications and healthcare costs. ICU nurses' knowledge, attitudes, and behavior in ENAD management significantly influence patient outcomes. OBJECTIVE: We evaluated ICU nurses' knowledge, attitudes, and behavior in ENAD management and explored their interrelationships using a social cognitive and behavior change framework. METHODS: From June 2022 to March 2023, 371 ICU nurses from 11 Chinese ICUs completed a validated questionnaire. We analyzed data using descriptive statistics, regression, and structural equation modeling. RESULTS: Knowledge (mean = 63.57, SD = 15.04), attitudes (mean = 44.19, SD = 4.76), and behaviors (mean = 56.32, SD = 9.15) were moderate. Knowledge was positively correlated with attitudes (ρ = 0.42, p < 0.001) and behaviors (ρ = 0.58, p < 0.001), and attitudes strongly correlated with behaviors (ρ = 0.65, p < 0.001). Attitudes mediated the knowledge-behavior relationship (β = 0.14, 95% CI [0.08, 0.21], p < 0.001). Master's Degree (β = 0.10, p = 0.049), training participation (β = 0.18, p = 0.002), and frequent training (4 times/year, β = 0.22, p < 0.001) predicted better knowledge, while training and age (31-35 years) enhanced attitudes (p < 0.05). CONCLUSION: Knowledge gaps hinder ICU nurses' ENAD management, with attitudes critically mediating the translation of knowledge into practice. Targeted interventions, such as quarterly workshops and scenario-based simulations, are recommended to enhance knowledge, foster positive attitudes, and standardize behaviors, thereby improving patient care quality.