Gastrointestinal mucormycosis, a rare fatal fungal infection in an immunocompromised host, affects mainly the stomach. Colonic mucormycosis is infrequent and is associated with high mortality. Perianal involvement is seen in almost one-third of patients with Crohn's disease. Perianal Crohn's disease is a particularly debilitating form of the disease, which requires multidisciplinary care. It may also require profound immunosuppression with biological agents to control disease activity. Opportunistic infections can complicate the disease course in these patients. We present a case of a middle-aged female with perianal Crohn's disease on adalimumab who developed colonic mucormycosis causing a flare in her disease activity. This patient highlights the need to increase awareness about fungal infections as a cause of disease flare in inflammatory bowel disease.