Selecting the most suitable warehouse site is a complex task involving multiple conflicting criteria, such as infrastructure, market, cost, and characteristics. These factors’ inherent ambiguity and uncertainty demand a structured and efficient decision-making method. Polytopic Fuzzy Sets (POFs) are well-suited to model such uncertain information. This study introduces an advanced Weighted Aggregated Sum Product Assessment (WASPAS) method based on POFs, utilizing the Weighted Average (WA) and Weighted Geometric (WG) to improve decision-making in warehouse site selection. A two-stage decision-making framework is then proposed, where criteria weights are determined through POFWA, and final rankings are computed using both the Weighted Sum Method (WSM) based on POFWA and the Weighted Product Method (WPM) based on POFWG. The effectiveness of this method is demonstrated through a case study on the selection of a warehouse site. Comparative analysis confirms the method’s reliability and superiority over existing approaches.