Older adults living with HIV (OALWH) comprise a growing population with a range of complex and interconnecting medical and psychosocial needs. Based on the biopsychosocial model with its emphasis on a holistic approach to various aspects of people's lives, the current study explored associations between physical health, psychological health, substance use, and overall quality of life. Drawing on data from 114 substance-using OALWH (aged 50 or older), we employed linear regression to show associations between the number of current comorbid health conditions on quality of life, over and above depression, substance use problems, and demographic characteristics (age, race/ethnicity, gender, sexual orientation, education, and relationship status). In both bivariate and multivariable contexts, the number of comorbid conditions was associated with reduced quality of life. Depression and substance use were also negatively associated with quality of life. These findings indicate that clinical and supportive care for OALWH, particularly when related to mental health and substance use, should also include an integrated focus on the comparatively high number of current comorbid conditions that often accompany, and potentially complicate, HIV treatment and quality of life.