<p>Temporomandibular joint disorder (TMD) often presents with otologic symptoms such as aural fullness, otalgia, and tinnitus, potentially linked to Eustachian tube dysfunction (ETD) due to anatomical and neuromuscular connections. Evidence from quantitative studies using validated ET assessment tools remains limited. The objective of this study was to determine the prevalence of ETD among adults with TMD and to assess factors associated with ETD in TMD patients. This cross-sectional observational study was conducted at a tertiary care hospital in Chengalpattu district with 90 newly diagnosed patients of TMD. Participants underwent structured history-taking, subjective assessment of ETD using ETFSI questionnaire, and objective assessment using tympanometry. ETD was defined as ETFSI score ≥ 14 and tympanometric curves which were flat, B type and C type. Data were analyzed using descriptive statistics, Chi-square test and bivariate analysis where <i>p</i> &lt; 0.05 was considered significant. Of the 90 participants, 23.3% reported clinically significant ETD on ETFSI scoring, while 20% showed negative middle ear pressure on tympanometry. Sixteen participants (17.8%) fulfilled both criteria and were classified as having ETD. Dysfunction was strongly associated with head and neck trauma, present in 31.3% of those affected compared with 2.7% without trauma. Similarly, ETD was more common in participants with bruxism (25%) and moderate pain (31.3%) compared with those without bruxism (2.7%) or minimal pain (6.3%). No associations were observed with age, gender, smoking, or allergy. ETD was present in 17.8% of TMD patients demonstrating a significant association between temporomandibular disorders and ETD, particularly in patients with trauma history, bruxism, and higher pain burden. The findings expand current understanding of the overlapping pathways between craniofacial and otologic systems, underscoring the need for multidisciplinary evaluation.</p>