Background Orthorexia Nervosa (ON) is an emerging clinical eating disorder characterized by an obsessive and pathological focus on healthy eating. In recent years, the Orthorexia Nervosa Inventory (ONI) has gained recognition as a promising tool for assessing orthorexic tendencies and behaviors, addressing the limitations of existing ON-specific measures. This study aimed to evaluate the psychometric properties of the Chinese version of the ONI. Methods A total of 717 participants (Mage = 20.11 years, 78.66% female) completed the Orthorexia Nervosa Inventory (ONI) alongside the Chinese version of the Düsseldorf Orthorexia Scale (C-DOS). The ONI was translated into Chinese using the Brislin traditional translation model, following formal authorization from the original author. This translation process included literal translation, back translation, and cultural adaptation to ensure both linguistic and contextual fidelity. Item analysis was employed to assess item differentiation, while the Delphi method was used to evaluate content validity. Scale reliability was determined by measuring internal consistency. Furthermore, exploratory and confirmatory factor analyses were conducted to investigate and confirm the underlying factor structure and overall validity of the scale. Results The Chinese version of the Orthorexia Nervosa Inventory (ONI) comprises 24 items across three dimensions. The Cronbach’s alpha coefficient for the overall scale was 0.922, with individual dimensions having coefficients of 0.930, 0.925, and 0.855, respectively. The Spearman-Brown split-half reliability coefficient was 0.931, and McDonald's ω was also 0.931, indicating strong reliability. The KMO value was 0.949, well above the acceptable threshold of 0.600, confirming the data's suitability for factor analysis. Principal Component Analysis (PCA) with varimax orthogonal rotation retained items with loadings greater than 0.40 on a single factor. The resulting three-factor structure explained 62.439% of the total variance. All model fit indices fell within acceptable ranges, affirming the structural validity of the Chinese version. The results from both exploratory and confirmatory factor analyses further supported this conclusion. Conclusion This study successfully translated and culturally adapted the ONI into Chinese, followed by a comprehensive evaluation of its psychometric properties. The findings demonstrate that the Chinese version of the ONI possesses strong reliability and validity. In the context of varying cultural backgrounds and dietary habits, this scale serves as a valid tool for assessing and screening the Chinese ON population.