To evaluate the utility of robot-assisted laparoscopic transabdominal preperitoneal repair (R-TAPP) of postprostatectomy inguinal hernia (PIH) in patients who underwent robot-assisted laparoscopic radical prostatectomy (RALP). This was a prospective, single-centre retrospective cohort study. R-TAPP was conducted in 74 consecutive patients from September 2016 to March 2020. With the exception of women and patients who underwent previous abdominal surgery, 70 patients were classified into two groups based on the absence or presence of PIH. Their data were retrospectively compared to those who had not undergone RALP. The median operative time for the PIH group was longer compared to the non-PIH group. However, postoperative complications, including seroma formation, haematoma and surgical site infections, were not significantly different between the groups. The estimated blood loss was small, and hospitalisation duration was 1 day in all cases. Moreover, there were no hernia recurrences within the 90-day follow-up period in either group. R-TAPP is a feasible and safe approach for inguinal hernia repair, even in patients who undergo RALP for prostate cancer.