Self-identification among lesbian, gay, transgender, queer, and other sexual minorities (LGBTQ+) is complex and multifaceted, yet few studies have examined its impact on immune parameters. The National Couples' Health and Time Study (NCHAT) is a nationally-representative cohort of 3,642 adult main respondents, ages 20 to 60 years, who are married or cohabiting, among whom 45 % self-identify as a non-heterosexual identity. Biological data were collected from a subset in the NCHAT Stress Biology study (NCHAT-BIO). The current analyses focus on data from 289 participants in NCHAT-BIO who identified as a non-heterosexual identity. Participants self-reported demographic, mental health, and LGBTQ+ identity items. Finger stick dried blood spot (DBS) sampling was self-administered by participants and assayed for C-reactive protein (CRP), interleukin-6 (IL-6), and antibodies against Epstein-Barr virus (EBV). Multivariable regression analyses were used to assess the relationship between each of the biomarkers and: 1) individual LGBTQ+ identity items and 2) latent profiles of LGBTQ+ identity items. Models were adjusted for demographic factors and other confounders. Among those assigned female at birth, a greater sense of pride in one's LGBTQ+ identity was associated with lower EBV antibody levels. Among those assigned male at birth, greater desire to keep one's identity private was associated with elevated CRP while those who would choose to be straight or wish they were heterosexual had elevated levels of IL-6. Meanwhile, being proud of one's LGBTQ+ identity predicted lower IL-6. These results provide novel evidence from a large sample that internalized stigma related to one's LGBTQ+ identity is associated with elevated inflammation and poorer cellular immune function while identity affirmation is associated with reduced inflammation. Future research should aim to develop and target both behavioral and biomedical interventions aimed at reducing health disparities among sexual minority populations.