Background <p>Unplanned readmission after esophagectomy is associated with increased health care costs and poorer survival outcomes. Postoperative physical activity during hospitalization may help mitigate this risk. This study evaluated the association between postoperative step count and 90-day unplanned readmission after curative thoracic esophagectomy and identified an optimal step count threshold for predicting readmission.</p> Methods <p>This retrospective cohort study analyzed 128 participants who underwent curative thoracic esophagectomy between 2016 and 2024. Step counts were recorded using a wearable activity tracker during the final 7 days before discharge. The primary outcome was unplanned readmission within 90 days after discharge. Multivariable logistic regression was used to identify independent predictors of readmission. A receiver operating characteristic curve determined the optimal step count cutoff.</p> Results <p>Unplanned readmission occurred for 27 participants (21.1%). Multivariable analysis indicated that a higher step count was independently associated with reduced readmission risk (odds ratio, 0.76 per 1000 steps; 95% confidence interval, 0.58–0.99 per 1000 steps; <i>p</i> = 0.044). The optimal cutoff for predicting readmission was 2446 steps per day (area under the curve, 0.691; sensitivity, 59.3%; specificity, 76.2%).</p> Conclusions <p>A lower pre-discharge step count independently predicted unplanned readmission after thoracic esophagectomy. A threshold of approximately 2500 or more steps per day may represent a practical target for postoperative rehabilitation and strategies to prevent readmission.</p>