Background Foramen tympanicum (FT) is a defect located anterior‐inferior to the external acoustic meatus. We evaluated its prevalence, location, size, and relationship with temporomandibular joint (TMJ) disorders. Methods Cone beam computed tomography was performed for 200 patients who presented to the Karamanoğlu Mehmetbey University Ahmet Keleşoğlu Faculty of Dentistry Hospital. The location and size of the FT in the axial and sagittal planes were evaluated. Descriptive statistics were used to compare the study parameters among age and sex groups. Patients with FT were reevaluated by two maxillofacial surgeons at the study centre. Results In total, 200 images from 400 joints were examined. Unilateral and bilateral FT (19 9.5% and 8 4%, respectively) was detected in 35 (17.5%) images from 27 (13.5%) patients. Examinations were performed for TMJ disorders in 24 patients. Participants with bilateral defects had the highest rates of presence of sounds and ear pain on the left and right sides (p < .05). Conclusion Foramen tympanicum can lead to TMJ disorders and spread of tumours or infections from the external auditory canal to the infratemporal fossa. The increased prevalence of such disorders in patients with bilateral FT suggests an association between them.