Chest trauma is a common injury in civilian and military polytrauma patients and is a leading cause of death and chronic disabilities. Evolving surgical techniques and advancements in chest wall reconstruction have improved clinical outcomes, reduced operative complications, and decreased mortality. In this case report, a 23-year-old male U.S. Army soldier sustained a left chest wall and shoulder blast injury with significant soft tissue damage, volumetric pectoralis major muscle loss, mild sensory nerve damage, and third-degree burns from a flashbang grenade. The initial treatment involved wound debridement, IV antibiotics, and pain management. This was followed by surgical reconstruction using a local advancement flap to prevent infection, address tissue loss, and restore chest wall integrity. Postoperative care included pain management and physical therapy, leading to a successful recovery with restored mobility and chest wall stability. This case highlights the challenges of treating severe chest wall trauma with burns, emphasizing the importance of timely surgical intervention and a multidisciplinary approach.