The relationship between stress, hair cortisol and alcohol consumption has mostly been investigated among clinical and adult study samples, with inconsistent findings. The present study aimed to examine cross-sectional and longitudinal associations between chronic stress, hair cortisol and average past-year alcohol consumption within a population-based sample of adolescents and young adults. At baseline of the epidemiological cohort study, N = 1180 individuals aged 14-21 from Dresden, Germany, were assessed (11/2015-12/2016). A maximum N = 1055 were analysed in cross-sectional analyses and a maximum N = 722 in longitudinal analyses (1-year follow-up). Multivariate linear regression analyses were conducted to reveal cross-sectional associations between perceived chronic stress, hair cortisol concentration and average past-year alcohol consumption in males and females. Longitudinally, weighted linear regression models examined relationships between (a) perceived chronic stress at baseline and altered hair cortisol concentration over 1 year, (b) perceived chronic stress/hair cortisol concentration at baseline and altered average alcohol consumption over 1 year and (c) average past-year alcohol consumption at baseline and altered stress/hair cortisol concentration over 1 year. Cross-sectionally, no significant relationships were found between stress, hair cortisol and average past-year alcohol consumption at baseline. In females, higher baseline perceived chronic stress was associated with an increase in hair cortisol concentration over 1 year, whereas no relationship was found in the cross-sectional analysis between baseline perceived chronic stress and baseline past-year average alcohol consumption. When using hair cortisol as a biomarker for stress perception, the focus of future research should be on potential time lags between perceived chronic stress and hair cortisol increase.