May-Thurner syndrome (MTS) is a vascular condition caused by extrinsic compression of the left common iliac vein by the right common iliac artery, predisposing patients to deep vein thrombosis (DVT). Though often asymptomatic, MTS can present with unilateral leg swelling and pain, particularly in young women without traditional risk factors. We present the case of a 45-year-old woman who developed acute left lower extremity DVT without prior medical history or provoking factors. Imaging confirmed extensive thrombosis and revealed complete iliac vein compression consistent with MTS. The patient underwent successful mechanical thrombectomy, stenting, and balloon angioplasty, followed by long-term anticoagulation. Two years post-intervention, she exhibited chronic venous changes but no recurrent DVT. This case highlights the importance of early diagnosis and endovascular management in symptomatic MTS to optimize outcomes and reduce long-term complications.