<p>Depression, anxiety, and stress significantly impact maternal mental health during the postpartum period, a time marked by heightened vulnerability to psychological distress. The Depression Anxiety Stress Scales (DASS-21) is a widely used tool for assessing these emotional states.A cross-sectional study was conducted with postpartum Czech mothers (<i>N</i> = 486) recruited online of whom 456 provided complete and valid responses for analysis. The survey included demographic questions, the Depression Anxiety Stress Scales (DASS-21), the Edinburgh Postnatal Depression Scale (EPDS), and the Social Support Survey Instrument (SSSI). The DASS-21 was translated through forward and backward translation. Confirmatory factor analysis and reliability tests were performed to validate its structure and consistency, with convergent and divergent validity assessed against EPDS scores and participant demographics.The CFA indicated that while the three-factor model was a viable representation of the data, the bifactor model demonstrated superior fit, capturing both general distress and specific factors of depression, anxiety, and stress. Internal consistency was high across subscales, and the Czech DASS-21 showed strong convergent validity with the Edinburgh Postnatal Depression Scale. Known-groups validity indicated significant score differences based on postpartum mental health status and infant health complications, supporting the tool’s utility for identifying psychological distress in this population.The CZ-DASS-21 is a valid and reliable tool for assessing postpartum psychological distress, offering a culturally appropriate measure to support maternal mental health screening and intervention.</p>