Lemierre's syndrome is characterized by internal jugular vein thrombosis and systemic septic embolism; it is a fatal complication of upper respiratory tract infections. To date, it has not been demonstrated how the upper respiratory tract inflammation spreads from the primary infection site to internal jugular vein and systemic thrombosis. We report a very rare case of Lemierre's syndrome derived from malignant otitis externa in which the spread of infection and thrombosis process were identified by imaging. A 61-year-old man with severe diabetes mellitus visited our hospital with consciousness disturbance and right posterior neck pain. He complained of right ear pain and otorrhea several days prior to the neck pain. Contrast-enhanced computed tomography demonstrated thrombosis in internal jugular vein and multiple lung abscesses. Temporal bone images revealed continuous lesions from skull base osteomyelitis to suboccipital abscess and sigmoid sinus thrombosis. We diagnosed the patient as having Lemierre's syndrome secondary to skull base osteomyelitis following malignant otitis externa. The patient clinically recovered with a combination of drainage of suboccipital abscess and long-term administration of antibiotics, which is the standard treatment of malignant otitis externa. Considering the details of imaging and bacterial examination is very useful for understanding the pathophysiology and determining appropriate treatment in Lemierre's syndrome pathophysiology and determining appropriate treatment in Lemierre's syndrome.