Abstract Background Incisional hernias are among the most frequent complications following abdominal surgery and cause substantial morbidity, impaired health-related quality of life and costs. Despite improvements in abdominal wall closure techniques, the risk for developing an incisional hernia is reported to be between 10 and 30% following midline laparotomies. There have been two recent innovations with promising results to reduce hernia risks, namely the small stitches technique and the placement of a prophylactic mesh. So far, these two techniques have not been evaluated in combination. Methods The HULC trial is a multicentre, randomized controlled, observer- and patient-blinded surgical effectiveness trial with two parallel study groups. A total of 812 patients scheduled for elective abdominal surgery via a midline laparotomy will be randomized in 12 centres after informed consent. Patients will be randomly assigned to the control group receiving closure of the midline incision with a slowly absorbable monofilament suture in the small stitches technique or to the intervention group, who will receive a small stitches closure followed by augmentation with a light-weight polypropylene mesh in the onlay technique. The primary endpoint will be the occurrence of incisional hernias, as defined by the European Hernia Society, within 24 months after surgery. Further perioperative parameters, as well as patient-reported outcomes, will be analysed as secondary outcomes. Discussion The HULC trial will address the yet unanswered question of whether a combination of small stitched fascial closure and onlay mesh augmentation after elective midline laparotomies reduces the risk of incisional hernias. The HULC trial marks the logical and innovative next step in the development of a safe abdominal closure technique. Trial registration German Clinical Trials Register, DRKS00017517. Registered on 24th June 2019.