Abdominal wall leiomyoma arising de novo is very rare, hence the reported imaging findings of this disease are also rare. We reported the case of a 33-year-old woman who presented with an abdominal wall mass without antecedent gynecological surgeries. The initial abdominal computed tomography (CT) showed thickening of the left rectus abdominis and the loss of intervening fat between the rectus abdominis and the lateral abdominal muscles. After 8 months, the follow-up contrast-enhanced CT and ultrasonography (US) showed a lentiform-shaped mass with isodensity to the adjacent muscles. The US-guided biopsy was consistent with leiomyoma.