Supernumerary teeth are dental units that appear in addition to the regular number of teeth. Their most frequent location is the anterior maxilla, especially on the maxillary midline, being called mesiodens, but also paramedian or in the position of a lateral incisor. On the other hand, the permanent canine is one of the most stable teeth regarding the number, with very few cases reported about hypo- or hyperdontia. This article reviews the few data found in the literature about the supernumerary permanent maxillary canine and also presents the case of an 8-year-old female patient with a supplemental permanent canine in the upper left maxilla. The patient was non-syndromic and did not present any other supernumerary teeth in the permanent dentition; she had only one in the temporary dentition. Using cone-beam computed tomography (CBCT) of the region, we were able to evaluate the position, structure, and shape of the supplemental canine and also to establish a treatment plan. The aim of this paper was to present this extremely rare case of a non-syndromic Romanian adult female patient with a unilateral supplemental permanent maxillary canine, and to include a literature review of the few reported such cases.