Objective This study aims to explore the relationship between socioeconomic status (SES) and intrinsic capacity (IC) in older adults, as well as the mediating role of healthy lifestyle. Methods Based on data from the Hubei Memory and Aging Cohort Study (HMACS), SES was assessed based on education, occupation, and income, and then categorized into high, medium, and low groups. Healthy lifestyle score (0-6 points) was constructed based on smoking, drinking, diet, social activities, physical exercise, and intellectual leisure activities. IC was assessed according to the indicators recommended by the WHO (2015). Group differences were compared using χ² tests or variance analysis. We performed a multivariable logistic regression analysis to assess the association between SES and IC impairment, and general linear regression models were used to analyze the association between SES and IC. A mediation model was employed to assess the mediating effect of healthy lifestyles on the association between SES and IC, with comparisons across sex and SES groups. Results A total of 5 628 eligible participants aged ≥60 years were included. Older adults with high SES had significantly higher healthy lifestyle scores than those with low SES (P<0.05). The IC impairment in the middle and low SES groups was 1.507 times (95% CI: 1.289-1.762) and 6.476 times (95% CI: 5.051-8.304) than that of the high SES group, respectively, both with P<0.001. SES and IC were significantly positively correlated (β=0.530, 95% CI: 0.505-0.555, P<0.001), with the strongest association in the low SES group (β=1.004,95% CI: 0.773-1.234, P<0.001). Healthy lifestyle partially mediated the relationship between SES and IC, with a mediation effect of 9.25%. The mediation effects were 8.32% in males and 10.19% in females. The mediation effect was significant only in the medium SES group (15.03%), with no significant mediation observed in the low or high SES groups. Conclusion In older adults, SES and IC are significantly positively correlated. SES is associated with IC both directly and indirectly through a healthy lifestyle, with mediating effects varying by sex and SES. Therefore, health promotion measures for older adults should fully consider sex and SES differences, emphasize the improvement of healthy lifestyles, enhance IC in older adults, and promote healthy aging.