Objective: To investigate the predictive value of lymphovascular space invasion (LVSI) for nodal recurrence and overall survival (OS) in patients with stage I endometrioid endometrial cancer (EC) following surgical staging that included adequate lymph node sampling. Methods: Retrospective analyses of patients undergoing surgical staging for FIGO stage I endometrioid EC between 1998 and 2015 were performed using an institutional database and the National Cancer Database (NCDB). Using the institutional database, logistic regression modeling identified predictors of nodal recurrence; Cox proportional hazards modeling was used to predict progression-free survival (PFS). Utilizing NCDB, Cox proportional hazards modeling was used to predict OS. The Kaplan-Meier method was used to estimate hazard ratios (HR). Survival curves were compared using the log-rank test. Results: Among 275 institutional cases, LVSI was present in 48 (17.5%). There were 11 nodal recurrences: 18.8% (9/48) of cases with LVSI had a nodal recurrence compared to 0.88% (2/227) of those without LVSI. In multivariate analysis of institutional data, LVSI was the only significant predictor of nodal recurrence (p = 0.002). Among 28,076 NCDB cases, LVSI was present in 3766 (13.5%). In multivariate analysis of NCDB, grade 3, LVSI, and depth of invasion (all p < 0.001) were prognostic for OS after adjusting for adjuvant radiation. Conclusion: LVSI is an independent prognostic factor for nodal recurrence in stage I endometrial cancer with lymph node assessment. LVSI is associated with lower OS in NCDB. Given these findings, adjuvant therapy could be considered in these patients.