Background This study aimed to explore the prognostic utility of the preoperative platelet‐to‐albumin ratio (PAR) among patients with oral cavity squamous cell carcinoma (OSCC). Methods We retrospectively reviewed of 355 patients with surgically‐treated OSCC between 2008 and 2017. The optimal PAR cutoff for patient stratification was determined through X‐tile analysis. Prognostic variables for disease‐free survival (DFS) and overall survival (OS) were identified using Cox proportional hazards models. We developed a PAR‐based nomogram to predict personalized OS. Results We determined the optimal PAR cutoff to be 7.45. A PAR of ≥7.45 was an independent negative prognostic factor for DFS and OS (hazard ratio = 1.748 and 2.386; p = 0.005 and p < 0.001, respectively). The developed nomogram demonstrates the practical utility of PAR and accurately predicts personalized OS. Conclusions The preoperative PAR is a promising and cost‐effective prognostic biomarker for patients with surgically‐treated OSCC; the PAR‐based nanogram accurately predicts OS for such patients.