Bilateral facial palsy, which is usually combined with other diseases, occurs infrequently. It may imply a life-threatening condition. Therefore, the differential diagnosis of bilateral facial palsy is important. However, the etiology is variable, which makes diagnosis challenging. We report a rare case of progressive bilateral facial palsy as a manifestation of granulomatosis with polyangiitis (GPA). A 40-year-old male with otitis media and right facial palsy was referred for electroneurography (ENoG), which showed a 7.7% ENoG. Left facial palsy occurred after 2 weeks, and multiple cavitary opacities were noted on chest images. GPA was diagnosed by lung biopsy. His symptoms deteriorated and mononeuropathy multiplex developed. The possibility of systemic disease, such as GPA, should be considered in patients presenting with bilateral facial palsy, the differential diagnosis of which is summarized in this report.