To evaluate the role of FloSeal for preventing symptomatic lymphocele following pelvic and/or para-aortic lymphadenectomy in patients with gynecological cancers. Between October 2014 and April 2015, 40 patients with gynecological cancers planned for surgical management were randomly placed into FloSeal and non-FloSeal groups in a 1:1 ratio. Lymphocele incidence was evaluated using intravenous contrast-enhanced, abdominopelvic computed tomography 3–6 months after surgery. The quality of life questionnaire was completed by patients at 1, 3 and 6 months after surgery. The incidence of symptomatic lymphocele was compared using a chi-square test. All patients underwent bilateral pelvic lymph node dissection, and eight patients in each group (40%vs. 44.4%, p > 0.999) underwent para-aortic lymph node dissection. The mean number of total, right pelvic, left pelvic and para-aortic lymph nodes retrieved was similar between the groups. One patient (1/20, 5%) in the FloSeal group and three (3/18, 16.7%) in the non-FloSeal group developed lymphoceles (p = 0.328). The incidence of symptomatic lymphocele was 0% and 11% (2/18) in the FloSeal and non-FloSeal groups (p = 0.218), respectively. The mean time interval to drain removal (4.8 ± 2.0 days vs. 5.3 ± 2.2 days, p = 0.400) was shorter and the mean drain volume (1656 ± 1362 mL vs. 2022 ± 2301 mL, p = 0.550) was smaller in FloSeal group. The use of FloSeal after pelvic and/or para-aortic lymphadenectomy in patients with gynecological cancers may be effective for preventing symptomatic lymphocele. Clinical Trial registration: NCT01679483.