<p>The Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) are widely used to measure depressive and anxiety symptoms in the general population and clinical practice. Although both measures are available in several languages, including Polish, no research has validated their psychometric properties in the general adult population of Poland, particularly regarding potential differences between age groups and genders. This study focuses on the psychometric validation of both measures across multiple samples. To achieve this, data from previous studies were combined, and two balanced subsamples were created based on the number of participants, age, gender, education level, and the severity of depression and anxiety. In the first subsample, Exploratory Factor Analysis (EFA) was conducted to assess the underlying constructs, while in the second subsample, Confirmatory Factor Analysis (CFA) with the WLSMV estimator was performed to test the factorial structure of the PHQ-9 and GAD-7 scales. Furthermore, differences in the severity of depression and anxiety symptoms based on gender and age were examined. EFA and CFA confirmed that both the PHQ-9 and GAD-7 strongly load onto a single factor, demonstrating satisfactory model fit. Moreover, both scales exhibited good internal consistency, confirming their reliability. Gender and age differences were observed, with women and younger adults (18–36 years) scoring higher on both measures than men and older adults (37–55 years). Approximately 30% of participants scored above the threshold for depressive disorders, and 23% for anxiety disorders. This study provides evidence for the validity and reliability of the PHQ-9 and GAD-7 in Poland’s general population and highlights the importance of considering gender and age when assessing mental health problems.</p>