Background Preoperative systemic inflammatory response plays a crucial role in tumorigenesis, progression, and prognosis; and neutrophil, monocyte, and lymphocyte counts serve as important biomarkers. An altered monocyte‐to‐lymphocyte ratio (MLR) and neutrophil‐to‐lymphocyte ratio (NLR) has been reported to be associated with a favorable prognosis for certain hematologic malignancies and breast cancer. The aim of this study was to investigate the prognostic significance of MLR, NLR in patients with resectable PNETs. Methods Patients undergoing surgery for PNETs between 2000 and 2016 were identified using a large, multi‐center database. NLR and MLR were calculated and Contal and O'Quigley analysis was used to determine the optimal cutoff value. Results A total of 620 patients were included in the analytic cohort. The prognostic implications of blood count parameters were evaluated in both univariate and multivariate analysis. The univariate analysis revealed that low MLR and NLR is associated with significantly improved overall survival (OS; P < .01) and recurrence‐free survival (RFS; P < .01). On multivariate analysis, in addition to tumor size and grade, NLR was an independent predictor of improved OS and RFS. Conclusion In addition to established tumor‐specific factors, preoperative NLR levels can serve as a valuable biomarker that can be used as a predictor of OS and RFS after resection of PNETs.