Plasma cell granuloma (PCG) is a mucosal condition characterised histologically by a dense aggregation of polyclonal plasma cells. There are limited reports in the literature of the condition affecting the oral mucosa and involvement of the gingival tissues is considered rare. The variable clinical presentation allows for a differential diagnosis of malignant conditions therefore awareness of the characteristics and distinctive histological features are important in avoiding misdiagnosis. We report a rare case of PCG presenting on the buccal gingivae of the posterior mandible, with concurrent mobility of the adjacent tooth, in a middle‐aged female. The clinical presentation of this lesion warranted urgent investigation, however, histological findings of a dense polyclonal plasma cell infiltrate revealed a benign PCG.