Posterior communicating artery (PCOM) aneurysms, even though rare, can lead to severe neurological deficits alongside life-threatening conditions, demanding rapid detection and intervention. We report a case of a 42-year-old male patient, known hypertensive, presenting with symptoms of headache, dizziness, and right-sided weakness. Imaging showed a saccular aneurysm in the left middle cerebral artery (MCA) alongside an acute-subacute subarachnoid hemorrhage. A subsequent computed tomography (CT) angiography established a large PCOM aneurysm. Above all, the aneurysm caused hemiparesis, a comparatively rare manifestation. Treated effectively through a balloon remodeling coiling technique, the patient recovered postoperatively. This case report also highlights the significance of timely recognition and the usefulness of endovascular coiling in treating PCOM aneurysms. Precisely, those patients presenting with atypical symptoms like hemiparesis lay stress on the need for strong clinical vigilance and further research to improve management strategies intended for these rare but critical conditions.