Objectives <p>To develop multivariate models for preoperative detection of occult lymph node (LN) metastasis in gastric cancer (GC), by integrating CT-based extracellular volume (ECV) fraction and clinicopathological features, and further evaluate the prognostic value of the combined model.</p> Materials and methods <p>This retrospective study included 129 GCs with the N (−) group (<i>n</i> = 49) and the N (+) group (<i>n</i> = 80). The preoperative CT parameters (including ECV fraction), WHO types and differentiation degree based on endoscopic pathological, and 4 hematological indices were assessed. The diagnostic performance of multivariate models was evaluated by receiver operating characteristic curve analysis.</p> Results <p>The N (+) group demonstrated significantly higher proportions of poorly cohesive carcinoma and poor differentiation based on endoscope (both <i>p</i> &lt; 0.001). Significantly higher CT-measured tumor area and ECV fraction were seen in the N (+) group (<i>p</i> &lt; 0.001 and <i>p</i> = 0.008, respectively), and a significantly higher proportion of ECV value &gt; 50% in the N (+) group (<i>p</i> = 0.001). The clinicopathological model, CT parameters model, and combined model yielded areas under the curves of 0.768, 0.774, and 0.843, respectively. The combined model with the high-risk group revealed a significantly shorter median recurrence-free survival compared to the low-risk group (<i>p</i> = 0.008).</p> Conclusion <p>The proposed preoperative combined model exhibited a promising performance for early predicting occult LN metastasis and stratifying postoperative recurrence risk in GC, by integrating CT-based ECV fraction and clinicopathological features.</p> Critical relevance statement <p>The CT-based ECV preoperative model could potentially provide valuable clinical reference for making clinical strategies in GC.</p> Key Points <p><UnorderedList Mark="Bullet"> <ItemContent> <p>It is a great challenge for clinicians to evaluate occult lymph node (LN) status in gastric cancer (GC).</p> </ItemContent> <ItemContent> <p>The N (+) group demonstrated higher CT-based extracellular volume (ECV) fractions and tumor area, and higher proportions of poorly cohesive carcinoma and poor differentiation.</p> </ItemContent> <ItemContent> <p>This model helped preoperative detection of occult LN metastasis and stratifying postoperative recurrence risk in GC.</p> </ItemContent> </UnorderedList></p> Graphical Abstract <p></p>