Introduction Mean platelet volume (MPV) is an inflammatory marker suggesting the activation of platelets. Many studies observed an association between MPV and cancer spread and metastasis. Hence, we have conducted a retrospective study to find the role of MPV as a prognostic marker in locally advanced gastric cancer. Materials and methods The present study included a retrospective review of 149 patients with gastric cancer who had neoadjuvant chemotherapy followed by surgery. MPV was obtained and then statistically analyzed to find an association between tumor (T), node (N), and overall stage as per the American Joint Committee on Cancer (AJCC) staging system, using Statistical Package for the Social Sciences (SPSS) software (IBM Corp., Armonk, NY). Results In our study, we observed that MPV values were significantly high in N+ disease (OR 3.794 (95% CI 1.903-7.563); p-value 0.0001), higher T stage (OR for >T2 3.692 (95% CI 1.876-7.266); pvalue 0.0001), and advanced stage (OR 7.708 (95% CI 3.258-18.237); p-value 0.0001) of gastric cancer. Conclusions MPV is an inflammatory marker that correlates with nodal disease and aids in the staging and prognostication of locally advanced gastric cancer. This inexpensive, convenient marker can aid in the risk stratification of locally advanced gastric cancer.