Background and Aims Intra-abdominal infection is a common complication after radical gastrectomy for gastric cancer. However, there are few studies concerning the influencing factors for intra-abdominal infection after robotic-assisted radical gastrectomy and the associated prognosis. Therefore, this study was conducted to analyze the risk factors for intra-abdominal infection after robotic-assisted radical gastrectomy and the associated prognosis, so as to provide a reference for clinical practice.Methods The clinical data of 262 gastric cancer patients undergoing robotic-assisted radical gastrectomy from January 2017 to March 2021 in the First Department of General Surgery, Gansu Provincial Hospital were reviewed. The incidence of postoperative intra-abdominal infection and its influencing factors as well as the influence of postoperative intra-abdominal infection on the treatment outcomes and prognosis of the patients were analyzed.Results Among the 262 patients, postoperative intra-abdominal infection occurred in 14 cases (5.34%). The causes for infection were intraperitoneal abscess in 12 cases (4.58%), transverse colon fistula in one case (0.38%) and pancreatic fistula in one case (0.38%), respectively; the Clavien-Dindo classification included grade II in 9 cases (3.44%), grade IIIa in 4 cases (1.53%), and grade IIIb in one case (0.38%). The results of univariate analysis showed that body mass index (BMI), preoperative albumin, preoperative anemia, tumor diameter, synchronous other organ resection, intraoperative blood loss, pTNM stage, N stage, lymphovascular invasion, nerve invasion and the percentage of neutrophils (NEUT%) on postoperative day (POD) 3 were significantly associated with the occurrence of intra-abdominal infection after robotic-assisted radical gastrectomy (all P<0.05). the results of multiple logistic regression analysis revealed that BMI <18.5 kg/m² (OR=11.160, 95% CI=2.289-54.410, P=0.003), preoperative albumin <30 g/L (OR=6.612, 95% CI=1.630-26.820, P=0.008), synchronous other organ resection (OR=5.236, 95% CI=1.068-25.661, P=0.041), tumor lymphovascular invasion (OR=8.151, 95% CI=1.771-37.52, P=0.007) and NEUT% on POD 3 (OR=1.208, 95% CI=1.069-1.366, P=0.003) were independent risk factors for intro-abdominal infection in patients after robotic-assisted radical gastrectomy. The results ROC curve analysis of the NEUT% on POD 1, 3 and 7 demonstrated that the NEUT% on POD 3 had the largest AUC (0.805) for diagnosis of intra-abdominal infection, with the cut-off value of 82.65%, sensitivity of 71.4% and specificity of 84.7%. In patients with postoperative intro-abdominal infection compared with those without intro-abdominal infection, the time to first gas passage, time to first food intake, volumes of abdominal drainage on POD 1 to 7, time to drainage tube removal, length of postoperative hospital stay and total medical cost were all significantly increased (all P<0.05). The results of survival analysis indicated that the overall survival rate of patients with intro-abdominal infection was lower than that of patients without intro-abdominal infection (45.4% vs. 67.8%, P=0.046).Conclusion For patients with above risk factors, aggressive preventive measures against intro-abdominal infection should be implemented after robotic-assisted radical gastrectomy, and thereby promotes the postoperative recovery and improves the postoperative prognosis of them. The NEUT% on POD 3 has certain application value for predicting intro-abdominal infection after robotic-assisted radical gastrectomy.