<p>In geotechnical engineering, unloading conditions such as excavation are commonly encountered, where accurate prediction of rebound deformation is critical for ensuring structural safety. Poisson’s ratio has a significant effect on rebound deformation, but it is typically taken as a constant (e.g., <i>v</i> = 0.2) in numerical calculations, which leads to inaccurate predictions of rebound deformation. This study proposes a new analytical method for estimating the Poisson’s ratio during unloading, based on stress data obtained from <i>K</i>₀-consolidation tests. The method assumes that the stress released during unloading is elastic and introduces a parameter, <i>K</i>_0<i>e</i>​, defined as the ratio of released horizontal stress to released vertical stress. A theoretical relationship between <i>K</i>_0<i>e</i>​ and Poisson’s ratio is derived from elastic theory, making it possible to estimate Poisson’s ratio without relying on strain measurements, which are not available during <i>K</i>₀ unloading. The results demonstrate that Poisson’s ratio is stress-dependent and increases with the overconsolidation ratio (<i>OCR</i>). The obtained stress-dependent Poisson’s ratio is incorporated into the incremental method, which addresses nonlinear problems in finite element analysis, to calculate rebound deformation and horizontal stress of soil during unloading. The computed results show good agreement with experimental data, whereas predictions based on a constant Poisson’s ratio show significant deviations. The proposed method provides a practical approach for predicting Poisson’s ratio during unloading and improves the accuracy of rebound deformation calculations in both engineering practice and numerical simulations.</p>