Background In patients with blunt injury due to abdominal trauma, the common cause for laparotomy is damage to the small bowel and mesentery. Recently, postoperative early enteral nutrition (EEN) has been recommended for abdominal surgery. However, EEN in patients with blunt bowel and/or mesenteric injury (BBMI) has not been established. Therefore, this study aimed to identify the factors that affect early postoperative small bowel obstruction (EPSBO) and the date of tolerance to solid food and defecation (SF + D) after surgery in patients with BBMI. Methods We retrospectively reviewed patients who underwent laparotomy for BBMI at a single regional trauma center between January 2013 and July 2021. A total of 257 patients were included to analyze the factors associated with enteral nutrition tolerance in patients with EPSBO and the postoperative day of tolerance to SF + D. Results The incidence of EPSBO in patients with BBMI was affected by male sex, small bowel organ injury scale (OIS) score, mesentery OIS score, amount of crystalloid, blood transfusion, and postoperative drain removal date. The higher the mesentery OIS score, the higher was the EPSBO incidence, whereas the small bowel OIS did not increase the incidence of EPSBO. The amount of crystalloid infused within 24 h; the amount of packed red blood cells, fresh frozen plasma, and platelet concentrate transfused; the time of drain removal; Injury Severity Score; and extremity abbreviated injury scale (AIS) score were correlated with the day of tolerance to SF + D. Multivariate analysis between the EPSBO and non-EPSBO groups identified mesentery and small bowel OIS scores as the factors related to EPSBO. Conclusion Mesenteric injury has a greater impact on EPSBO than small bowel injury. Further research is needed to determine whether the mesentery OIS score should be considered during EEN in patients with BBMI. The amount of crystalloid infused and transfused blood components within 24 h, time of drain removal, injury severity score, and extremity AIS score are related to the postoperative day on which patients can tolerate SF + D.