Background <p>Age-related hearing loss (ARHL) is common among older adults, and moderate-to-severe hearing loss (HL) is associated with adverse health outcomes. This study aimed to determine the prevalence of moderate-to-severe HL, identify its association with age, and assess potential sex differences across age groups.</p> Methods <p>This cross-sectional study included 2465 older adults from the China National Health Survey (between April and November 2023). Associations between age and HL were assessed using modified Poisson regression with robust variance. Multiplicative interaction terms were included to evaluate effect modification by sex.</p> Results <p>Overall, 26.8%, 19.1%, and 66.8% of older participants had moderate-to-severe HL in speech-, low-, and high-frequency ranges, respectively. Compared with the lowest quartile of age, the adjusted prevalence ratios for the highest quartile were 3.61 (95% CI, 2.90–4.50) for speech-frequency HL, 4.98 (95% CI, 3.69–6.70) for low-frequency HL, and 1.58 (95% CI, 1.45–1.71) for high-frequency HL(all <i>P</i> for trend &lt; 0.001). Stratified analyses showed positive associations between age and HL across all frequency ranges in both sexes. A significant age × sex interaction was observed, indicating sex-specific age-related patterns of HL. Relative to the youngest age group (Q1), women showed a greater increase in the prevalence of moderate-to-severe HL across higher age groups than men.</p> Conclusion <p>Increasing age was associated with a higher prevalence of moderate-to-severe HL across speech-, low-, and high-frequency ranges, with stronger age-related effects observed in women. These findings underscore the importance of early hearing assessment in older adults, and future research should investigate longitudinal changes, particularly the potential role of estrogen fluctuations around menopause in women.</p>