Due to the growing evidence of sentinel lymph node (SLN) mapping in endometrial cancer (EC), our aim was to evaluate the impact of SLN mapping and other clinical-pathological variables in the risk of developing lymphocele. We retrospectively analyzed a series of patients with ECs who underwent lymph node staging with SLN mapping with or without systematic pelvic ± para-aortic lymphadenectomy from November 2012 to January 2020. The lymphocele diagnosis was performed by computed tomography or magnetic resonance imaging. Of 348 patients included, 178 underwent SLN mapping only and 170 underwent SLN mapping and systematic lymphadenectomy (46.5% pelvic only; 53.5% pelvic and para-aortic). Seventy-three (21%) patients had open surgery and 275 (79%) had a minimally invasive approach. After a median follow-up of 25.4 months, the overall prevalence of lymphocele was 8.6% (n = 30), with 29 cases in a pelvic location. Lymphocele was found in 3.4% (n = 6/178) of patients submitted to SLN mapping only, compared with 14.1% (n = 24/170) among those who underwent SLN with lymphadenectomy (p = 0.009). Among those patients with lymphocele, seven (23.3%) were symptomatic and five (16.6%) required drainage. All symptomatic cases occurred in lymphoceles larger than 4 cm (p = 0.001). Neither resected lymph node count nor the type of systematic lymphadenectomy were related to the presence of lymphocele. Systematic lymphadenectomy was the only factor that emerged as a risk factor for the presence of lymphocele in multivariate analysis (odds ratio 3.68, 95% confidence interval 1.39–9.79; p = 0.009). Our data suggest that SLN mapping independently decreases the risk of lymphocele formation compared with full lymphadenectomy in EC.