We conducted a cross-sectional study among HIV-positive adults age ≥ 50 in San Francisco to evaluate the frequency of loneliness, characteristics of those who reported loneliness, and the association of loneliness with functional impairment and health-related quality of life (HRQoL). Participants (N = 356) were predominately male (85%); 57% were white; median age was 56. 58% reported any loneliness symptoms with 24% reporting mild, 22% moderate and 12% severe loneliness. Lonely participants were more likely to report depression, alcohol and tobacco use, and have fewer relationships. In unadjusted models, loneliness was associated with functional impairment and poor HRQoL. In adjusted models, low income and depression remained associated with poor HRQoL, while low income, higher VACS index and depression were associated with functional impairment. A comprehensive care approach, incorporating mental health and psychosocial assessments with more traditional clinical assessments, will be needed to improve health outcomes for the aging HIV-positive population.