Extensive cerebral sinus thrombosis following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is rare. We report the case of a 42-year-old man who presented with a severe generalized headache that was not relieved by analgesics for nine days. It started four days after he received the third dose of BNT162b2 (BioNTech/Pfizer). He also complained of numbness at the back of the neck, vomiting, mild blurring of vision, and diplopia. The visual acuity (VA) in the right eye was 6/9 (improved to 6/7.5 with a pinhole) and 6/6 in the left eye. He was not able to abduct both eyes and noticed a double image at lateral gaze. Fundoscopy showed swollen optic discs with the presence of disc hemorrhages. A computed tomography venogram (CTV) of the brain showed loss of normal signal void with filling defects in the superior sagittal sinus, straight sinus, bilateral transverse sinuses, bilateral sigmoid sinuses, and bilateral internal jugular veins. The nasopharyngeal swab sample was negative for SARS-CoV-2. His platelet was normal (271x109/L) and his coagulation profile was normal. Workup for connective tissue disease was negative. He was diagnosed with extensive cerebral vascular thrombosis post-vaccination. He received a one-week course of subcutaneous clexane, followed by oral anticoagulant treatment. After treatment, his headache was relieved, and the diplopia subsided. The venous thrombosis was partially resolved. Both the swollen optic discs improved, and his VA improved to 6/6 in both eyes.