Maxillary sinusitis is a recognized complication following dental procedures, but its occurrence after orthognathic surgery, such as Le Fort osteotomies, remains less documented. This case report presents a 58‐year‐old female who developed unilateral maxillary sinusitis 23 years post‐orthognathic surgery. The patient was asymptomatic, aside from occasional cacosmia, and was incidentally found to have sinus opacification on a computed tomography (CT) scan performed for implant‐prosthetic rehabilitation. Nasal endoscopy revealed purulence and mucosal edema, prompting endoscopic sinus surgery (ESS). Intraoperatively, purulent material and fungal debris were removed from the maxillary sinus, confirming bacterial sinusitis with a concurrent fungal ball. S. salivarius and Klebsiella species were identified from the cultures. The patient's condition improved following the removal of both the sinus contents and the retained titanium plates and screws. This case underscores the potential for maxillary sinusitis to develop long after orthognathic surgery, particularly in the presence of retained dental hardware. It highlights the importance of thorough imaging and endoscopic evaluation in patients with a history of dental or facial surgeries presenting with sinonasal symptoms. Additionally, it raises questions about the role of retained hardware in the persistence or recurrence of infection and the possible association with fungal ball formation. The need for further research to establish guidelines for the management of sinusitis in such contexts, particularly regarding the removal of facial hardware, is emphasized.