Peritonsillar abscess is a common deep throat infection. Early diagnosis and prompt, appropriate management of a peritonsillar abscess prevents mortality. A 45-year-old woman on steroids for an ulcerative colitis (UC) exacerbation presented with sore throat and multiple skin ulcers on her left forearm and right foot. Computed tomography of the neck revealed a peritonsillar abscess. Gram staining and culture of the abscess were negative, and a skin biopsy suggested pyoderma gangrenosum (PG). The final diagnosis was peritonsillar involvement of steroid-refractory PG-associated UC. The patient showed a complete response to infliximab. Here, we report a case of successful infliximab treatment for peritonsillar involvement of steroid-refractory PG-associated UC.