Background: This study explores the association of demographic and clinical features with quality of life and functioning in individuals with bipolar disorder. Methods: Adult participants (N = 482) with bipolar I or II disorder were enrolled in a comparative effectiveness study across eleven study sites and completed baseline measures of medical and psychiatric history, current mood, quality of life, and functioning. Participants with at least mildly depressive or manic/hypomanic symptomatic severity were randomized to receive lithium or quetiapine in addition to adjunctive personalized treatment for 6 months. Results: Participants with more severe depressive and irritability symptoms had lower quality of life and higher functional impairment. All psychiatric comorbid conditions except substance use disorder were associated with worse quality of life. On average, females had lower quality of life than males. Patients who were married, living as married, divorced, or separated had worse functional impairment compared with patients who were single or never married. A composite score of social disadvantage was associated with worse functioning and marginally associated with worse quality of life. Symptom severity did not moderate the effect of social disadvantage on quality of life or functioning. Conclusions: Our findings highlight that depression, irritability, and psychiatric comorbid conditions negatively impact quality of life and functioning in bipolar disorder. The study suggests that individuals with social disadvantage are at risk for functional impairment.