Abstract Background Young adults are disproportionately affected by mental health problems such as depression and anxiety. While previous studies have identified sociodemographic predictors using the four-item Patient Health Questionnaire (PHQ-4), differences in symptom severity remain less explored. This study aimed to evaluate the sociodemographic predictors of different levels of depression and anxiety symptoms among young adults in Sweden. Methods Survey data from a population-based sample of Swedish adults aged 20-21 (n = 3,226) was used. Symptom severity was categorized into three levels: normal/mild, moderate, and severe, based on established cutoff scores on the PHQ-4. Gender, parental education and birth country, and upper secondary education were assessed through linked registry information. Multinomial logistic regression was used. Results Females had a higher risk of moderate (RR = 1.8, 95% CI 1.5, 2.2) and severe (RR = 2.3, 95% CI 1.8, 3.1) symptoms (compared to no or mild symptoms) relative to males. Among males, the risk of moderate symptoms was higher without a secondary degree (RR = 1.9, 95% CI 1.0, 3.4) compared to an academic degree. Males with parents born abroad faced elevated risks of moderate (RR = 1.9, 95% CI 1.3, 2.9) and severe (RR = 2.2, 95% CI 1.3, 3.7) symptoms relative to males with Swedish-born parents. Among females, parental tertiary education was associated with a lower risk of moderate symptoms (RR = 0.7, 95% CI 0.5, 0.9) compared to lower education. Further, females having a vocational (RR = 1.5, 95% CI 1.1, 2.1) or no secondary degree (RR = 3.6, 95% CI 2.1, 6.1) had an increased risk of severe symptoms compared to females with an academic degree. Conclusions This study identified sociodemographic predictors for moderate and severe symptoms of depression and anxiety among young men and women in Sweden. Mental health promotion and prevention should specifically target young adults at elevated risk of experiencing moderate to severe symptoms. Key messages • Understanding sociodemographic predictors of depression and anxiety symptoms in young adulthood is essential for public health work. • Mental health promotion and prevention needs to include appropriate interventions for young men and women from diverse socioeconomic and cultural backgrounds.