Violence victimization has been associated with low-grade inflammation. Lesbian, Gay, and Bisexual (LGB) individuals are at greater risk for victimization in childhood and young adulthood compared to heterosexuals. Moreover, the intersection of LGB identity with gender, race/ethnicity, and educational attainment may be differentially associated with victimization rates. However, no previous study has examined the role of cumulative life-course victimization during childhood and young adulthood in the association between 1) LGB identity and low-grade inflammation during the transition to midlife, and 2) intersection of LGB identity with gender, race/ethnicity, and educational attainment and low-grade inflammation during the transition to midlife. We utilized multi-wave data from a national sample of adults entering midlife in the United States- the National Longitudinal Study of Adolescent to Adult Health (Add Health; n = 4573) - and tested four bootstrapped mediation models. Results indicate LGB identity, LGB and White, and LGB and Black identities were indirectly associated with low-grade inflammation during the transition to midlife via higher levels of cumulative life-course victimization. Moreover, among LGB adults, the association between 1) less than college education and 2) some college education, and low-grade inflammation was mediated by cumulative life-course victimization. For LGB females, there was a direct association between identity and low-grade inflammation and this association was mediated by cumulative life-course victimization . Reducing accumulation of victimization could be critical for preventing biological dysregulation and disease onset among LGB individuals, particularly for those with multiple marginalized identities.