Abstract Odontogenic keratocyst (OKC) arising from purely soft tissue other than the mucosa covering the jawbone is rare. A 57- year-old Korean female patient presented with a lump on her right cheek, which had been suspected as a fibrotic mass on the buccinator muscle by the local clinic. Magnetic resonance imaging showed an ovoid mass in the buccal space just before the right ramus with an enhancing component in the marginal area, and the interior of the mass revealed a fluid signal. Histopathologically, the lesion showed the typical features of OKC and the cyst wall contained some daughter cysts and the minor salivary gland, muscle, and fat tissues. The authors report a very unique case of OKC arising in the masseter muscle.