Objectives Understanding the factors that contribute to treatment-seeking attitudes among older adults—a growing population with frequent mental health concerns—is vital. Although past research has identified some demographic and belief-based predictors of mental health treatment attitudes among this population, previous studies are limited by only evaluating these variables in isolation and not distinguishing between different types of treatment (e.g. medication and psychotherapy). Methods In a pre-registered online survey of 606 older adults (age 60 years and older), we evaluated stigmatizing attitudes, etiological beliefs about depression, psychological symptoms, and health literacy as well as attitudes about psychotherapy and medication separately. Results Pre-registered linear regression analyses showed that greater stigmatizing attitudes uniquely predicted more negative attitudes for both therapy and medication treatment seeking over and above gender, education, income, extrinsic barriers, health literacy, depression, and anxiety. Additionally, loneliness was a significant predictor of less favorable medication attitudes. Exploratory analysis revealed that attributing depression to a chemical imbalance predicted positive attitudes about medication, but not psychotherapy. Conclusion These findings indicate that older adults’ treatment-seeking behaviors are separately influenced by stigma, etiological beliefs, and loneliness.