Alkaline phosphatase placental-like 2 (ALPPL2) is a member of the ALPP alkaline phosphatase family and is reported to be associated with the growth of some tumors. Gastric cancer is one of the most common cancers worldwide. We previously identified a distinct expression pattern of ALPPL2 between gastric cancer and adjacent normal tissues. In this study, we examined the expression of ALPPL2 in gastric adenocarcinoma and its ability to predict prognosis. We used bioinformatics analysis and immunohistochemistry to examine the expression pattern of ALPPL2 and analyzed the associations between ALPPL2 level and perioperative characteristics and the prognosis of gastric adenocarcinoma patients by Kaplan-Meier plotter analysis. Our results indicated that the expression of ALPPL2 was significantly increased in gastric adenocarcinoma (P < .01) and was an independent factor (P < .05) that could provide reliable prognostic information on gastric adenocarcinoma patients. High expression of ALPPL2 was associated with advanced TNM stage (P < .05) and high HER-2 expression (P < .01). Our study suggests that ALPPL2 has the potential to reveal prognostic information on gastric cancer.