Postoperative nausea and vomiting (PONV) is a common side effect after laparoscopic surgery. The aim of the study is to investigate the variables that could predict PONV in patients who underwent laparoscopic gastrectomy. We divided patients who underwent laparoscopic gastrectomy into PONV and No-PONV groups. Propensity score matching (PSM) was applied to adjust confounding factors for further validation, and ordinal logistic regression analysis was used to identify predictors for PONV. In the ordinal logistic regression analysis, the preoperative neutrophil-to-lymphocyte ratio (NLR) (odds ratio [OR]: 3.19, 95% confidence interval [CI]: 1.38–7.38; p < 0.01) was identified as an independent risk factor for the presence of PONV and a predictor of the severity of PONV (OR: 3.44, 95% CI: 1.67–5.20; p < 0.01) in 94 PSM patients. Besides, NLR was positively correlated with the PONV score (r = 0.534, p < 0.001). In the receiver-operating characteristic (ROC) curve analysis, an NLR with an optimal cutoff value of 1.59 predicted severe PONV with a sensitivity of 72% and specificity of 81%. The NLR was an independent risk factor for the presence of PONV, and a high NLR tends to be positively associated with the severity of PONV after laparoscopic gastrectomy.