(1) Explore associations between county minority health social vulnerability index (MH-SVI) and total joint replacement (TJR), and (2) assess associations by individual-level race/ethnicity. An expanded understanding of relevant social determinants of health is essential to inform policies and practices that promote equitable access to hip and knee TJR. Retrospective cohort study of Medicare enrollees. Centers for Medicare and Medicaid Services claims data were linked with MH-SVI. Multivariable logistic regression models were used to evaluate the odds of TJR according to the MH-SVI quartile in which enrollees resided. A total of 10,471,413 traditional Medicare enrollees in 2018 aged 67 years or older with arthritis. The main outcome was enrollee primary TJR during hospitalization. The main exposure was the MH-SVI (composite and 6 themes) for the county of enrollee residence. Results were stratified by enrollee race/ethnicity. Asian American, Native Hawaiian, or Pacific Islander (AANHPI), Black or African American (Black), and Hispanic enrollees comparatively had 26%-41% lower odds of receiving TJR than White enrollees. Residing in counties within the highest quartile of composite and socioeconomic status vulnerability measures were associated with lower TJR overall and by race/ethnicity. Residing in counties with increased medical vulnerability for Black and White enrollees, housing type and transportation vulnerability for AANHPI and Hispanic enrollees, minority status and language theme for AANHPI enrollees, and household composition vulnerability for White enrollees were also associated with lower TJR. Higher levels of social vulnerability were associated with lower TJR. However, the association varied by individual race/ethnicity. Implementing multisectoral strategies is crucial for ensuring equitable access to care.