BackgroundWhether endoscopic submucosal dissection (ESD) applies to undifferentiated-type early gastric cancer (UEGC) remains controversial. We aimed to analyze the risk factors for lymph node metastasis (LNM) in UEGC and evaluate the feasibility of ESD.MethodsThis study included 346 patients with UEGC who underwent curative gastrectomy between January 2014 and December 2021. Univariate and multivariate analyses of the correlation between clinicopathological features and LNM were conducted, and the risk factors for exceeding the expanded ESD indications were evaluated.ResultsThe overall LNM rate in UEGC was 19.94%. Among the preoperatively assessable factors, submucosal invasion (odds ratio [OR] = 4.77, 95% confidence interval [CI]: 2.14–10.66) and > 2 cm(OR = 2.49, 95% CI: 1.20–5.15) were independent risk factors for LNM, while postoperative independent risk factors were > 2 cm (OR = 3.35, 95% CI: 1.02–5.40) and lymphovascular invasion(OR = 13.21, 95% CI: 5.18–33.70). Patients who met the expanded indications had a low LNM risk (4.1%). Additionally, tumors located in the cardia (P= 0.03), non-elevated type (P< 0.01) were independent risk factors for exceeding the expanded indications in UEGC.ConclusionsESD may be applicable for UEGC meeting the expanded indications, and preoperative evaluation should be cautious when the lesion is non-elevated type or located in the cardia.Trial registrationChinese Clinical Trial Registry (12/05/2022ChiCTR2200059841).Supplementary InformationThe online version contains supplementary material available at 10.1186/s12876-023-02771-x.