Adolescent life satisfaction is crucial to later adult health and well-being; therefore, searching for its correlates should receive priority in research. The aim of this study was to explore the role of psychological (depression, future orientation), school-related (school achievement, satisfaction with school), religious (going to church, importance of religion), socially supportive (family and friend support), other familial, and sociodemographic (age, sex, self-assessed socioeconomic status) factors in adolescent life satisfaction. This cross-sectional survey (entitled Szeged Youth Study 2022) involved a sample of middle and high school students (N = 2239, aged 11–18 years, 51.8% females) from public schools in Szeged, Hungary. Besides descriptive statistics, correlation and multiple regression analysis were applied to the data analyses. Boys scored higher on the life satisfaction scale (Satisfaction with Life Scale, SWLS), while the level of depression (Children’s Depression Inventory, CDI) was higher among girls. In the final regression model, family support was the strongest predictor of life satisfaction (β = 0.44, p < 0.001), followed by depression (as a negative contributor), socioeconomic (SES) self-assessment, future orientation, satisfaction with school, going to church, and friend support. School prevention programs should be focused not only on preventing mental health difficulties but also promoting adolescent well-being.