Purpose <p>To evaluate the effect of internal ring defect closure on seroma prevention after laparoscopic transabdominal preperitoneal inguinal hernia repair (TAPP).</p> Methods <p>We conducted a randomized controlled trial including male patients aged 18–75 years with indirect inguinal hernia classified as L3 (defect ≥ 3&#xa0;cm). Participants were randomly assigned to undergo TAPP with internal ring closure (DC group) or none closure (NC group). Primary outcomes were operative time and postoperative seroma incidence, assessed by clinical examination and ultrasonography at 7 days, 1 month, and 3 months. Secondary outcomes included postoperative pain, recurrence, hospital stay, and complications.</p> Results <p>A total of 76 patients were randomized (DC, <i>n</i> = 38; NC, <i>n</i> = 38). Baseline characteristics were comparable between groups. During the 90-day follow-up period, postoperative seroma occurred in 3 patients in the DC group and 10 patients in the NC group. Kaplan–Meier analysis demonstrated a significantly higher seroma-free survival rate in the DC group than in the NC group (log-rank <i>P</i> = 0.0335). No significant differences were observed in operative time, postoperative pain, length of hospital stay, recurrence, or other postoperative complications.</p> Conclusions <p>Internal ring defect closure during TAPP repair significantly improves seroma-free survival and reduces the incidence of early postoperative seroma without increasing operative risk, postoperative pain, or morbidity.Although recurrence was not observed, the relatively small sample size and limited follow-up warrant cautious interpretation. Larger multicenter studies with extended surveillance are needed to validate these findings and define the role of internal ring closure in optimizing outcomes after laparoscopic inguinal hernia repair.</p>