Introduction: Desmoid tumors are rare, benign fibroblastic neoplasms characterized by locally aggressive behavior and high recurrence rates. Abdominal wall desmoid tumors show a strong association with pregnancy and prior abdominal surgery. Case Presentation: A 28-year-old female presented with a gradually progressive anterior abdominal wall mass one year following childbirth. She had a history of laparoscopic intraperitoneal onlay mesh (IPOM) repair for umbilical hernia performed during an undetected early pregnancy. Imaging revealed a large intramuscular mass arising from the rectus abdominis muscle. The patient underwent wide local excision of tumor with abdominal wall reconstruction using composite mesh. Histopathology confirmed intra-abdominal fibromatosis with negative surgical margins. Clinical Discussion: Hormonal influences related to pregnancy and antecedent surgical trauma are recognized contributors to desmoid tumor development. Complete surgical excision remains the primary treatment for symptomatic abdominal wall desmoid tumors, although recurrence rates remain significant. Conclusion: This case highlights the multifactorial pathogenesis of abdominal wall desmoid tumors in the postpartum period and underscores the importance of early diagnosis, complete surgical excision, and long-term follow-up.