Infectious tenosynovitis can involve both flexor and extensor tendons of the extremities. If left untreated, it can lead to high morbidity and mortality. Most emergency providers recognize the signs and symptoms of flexor and extensor tenosynovitis of the hand. However, extensor tenosynovitis of the hallucis longus tendon is a rare condition with a risk of complications similar to infectious tenosynovitis of the hand. This case report describes a presentation of extensor tenosynovitis of the hallucis longus tendon. Clinical suspicion is essential to help the provider not miss this rare condition, which can lead to significant morbidity if not treated promptly or appropriately.