Loneliness, an emerging public health problem, is higher among people living with HIV and is associated with negative health outcomes. Black/African Americans have a high burden of HIV, and little is known about the characteristics of loneliness among Black adults living with HIV; therefore, this study sought to understand the sociodemographic and psychosocial correlates of Black adults living with HIV who are lonely and the implications of loneliness for their health outcomes. A sample of 304 Black adults living with HIV (73.8% sexual minority men) in Los Angeles County, CA, USA, completed the survey items assessing sociodemographic and psychosocial characteristics, social determinants of health, health outcomes, and loneliness. Antiretroviral therapy (ART) adherence was assessed electronically with the medication event monitoring system. Bivariate linear regressions analysis showed higher loneliness scores among those with higher levels of internalized HIV stigma, depression, unmet needs, and discrimination related to HIV serostatus, race, and sexual orientation. In addition, participants who were married or living with a partner, had stable housing, and reported receiving more social support had lower levels of loneliness. In multivariable regression models controlling for correlates of loneliness, loneliness was found to be a significant independent predictor of worse general physical health, worse general mental health, and greater depression. Loneliness was marginally associated with lower ART adherence. Findings suggest that Black adults living with HIV, who experience multiple intersectional stigmas, require targeted interventions and resources.