ObjectiveTo explore the association between body composition and sensorineural hearing loss (SNHL).Study DesignCross‐sectional study, prospective study and Mendelian randomization (MR) analyses.SettingUK Biobank.MethodsThis cross‐sectional study included 147,296 adult participants with complete data on body composition and the speech‐reception‐threshold (SRT) test. We further conducted a prospective study with 129,905 participants without SNHL at baseline and followed up to 15 years to explore the association between body composition and new‐onset SNHL. Multivariable logistic regression and Cox regression models were used. Subgroup analyses stratified by age and sex were performed. We further assessed the causal association between body composition and SNHL using two‐sample MR analyses.ResultsOur cross‐sectional study revealed that fat percentage, especially leg (odds ratio [OR] 1.46, p = .029) and arm (OR 1.43, p = .004), were significant risk factors for SNHL. However, fat‐free mass, especially in the arm (OR 0.27, p < .001) and leg (OR 0.58, p < .001) showed significant protective effects against SNHL, which was substantially consistent with the results of the prospective study. In addition, we found that young women with SNHL were more susceptible to body composition indicators. However, MR analyses revealed no evidence of significant causal association.ConclusionFat percentage, especially in the leg and arm, was a significant risk factor for SNHL, whereas fat‐free mass, especially in the leg and arm, had significant protective effects against SNHL, however, these associations may not be causal.