For patients with low-grade endometrioid carcinoma of stage T1a, the role of lymphadenectomy in staging surgery remains controversial. This study aims to evaluate the impact of lymphadenectomy on cancer-specific survival (CSS) in this patient population using a large, population-based dataset. We conducted a retrospective analysis using the Surveillance, Epidemiology, and End Results (SEER) database, identifying 11,014 patients with stage T1a, low-grade endometrioid carcinoma from 2004 to 2015. Patients were divided into lymphadenectomy and non-lymphadenectomy groups. Propensity score matching (PSM) was performed to balance baseline characteristics. Kaplan-Meier analysis, log-rank tests, and multivariate Cox regression were used to assess CSS and identify independent prognostic factors. Before PSM, the non-lymphadenectomy group had higher CSS compared to the lymphadenectomy group (HR = 1.56, 95% CI: 1.16-2.10, p = .003). After 1:1 PSM, CSS was similar between the two groups (HR = 1.09, 95% CI: 0.78-1.53, p = .605). Subgroup analyses showed no significant differences in CSS except for the subgroup with tumor size > 2 cm, where non-lymphadenectomy was associated with better CSS (HR = 0.50, p = .035). Multivariate Cox regression analysis identified age, marital status, histological grade, and chemotherapy as independent prognostic factors for CSS, while lymphadenectomy was not (p = .980).. Our findings suggest that lymphadenectomy does not improve CSS in patients with low-grade endometrioid carcinoma of stage T1a.