Abstract Background Minimally invasive hiatal hernia (HH) repair is usually a safe procedure with low morbidity; however, a subset of patients may require intensive care unit (ICU) admission. To date, no specific and validated tool is available to predict the risk of ICU admission after HH repair. Although multiple tools to predict the risk of admission to the ICU after major surgical procedures have been reported, most of them are complex and require laboratory parameters. We propose a novel and quick intraoperative score that is useful for assessing unexpected ICU admission and tailoring patient management during HH repair. Methods A development cohort was established using a prospectively maintained database containing demographic, clinical, and surgical information of consecutive patients who underwent HH repair between September 2016 and July 2023. Clinical expertise and multiple logistic regressions were employed to select adequate demographic or surgical predictors to create an intuitive risk score (PHOENIX-HH). Further, a specific scoring system for each included variable was designated, and the total score (a scale from 0 to 9 points) was assessed for accuracy using the area under the receiver operating characteristic curve (AUC-ROC). Results The development cohort was formed by 391 patients who underwent primary HH repair (73.7% women; mean age 64.4±12.5 years; mean BMI 28.9±4.9 kg/m2). The mean AUC in the development cohort was 0.845 (95%CI: 0.756-0.934), and when defining a cut-off of ≥6 points, 12 of 15 patients who required ICU admission were identified using the proposed score (sensitivity, 80% [95%CI: 51.9-95.7%]; specificity, 80.1% [95%CI: 75.7-84%]; positive likelihood ratio, 4.0 [95%CI: 2.9-5.6]; negative predictive value, 99.0% [95%CI: 97.3-99.6%]). Conclusion The strongest predictor for unexpected ICU admission and postoperative complications following HH repair was the HH size (defined as the percentage of intrathoracic stomach); hence, the incorporation of this variable and other preoperative and intraoperative factors into a scoring system led to the development of the PHOENIX-HH score. This tool may allow early identification of patients who may require admission to the ICU after the surgery. Future validation using an external cohort is highly desirable.