Objective: Social jetlag, a form of chronic circadian misalignment, has previously been associated with obesity in adults. We aimed to investigate the association between social jetlag and obesity-related characteristics in Dutch adolescents over a 1-year period. Methods: We analysed data of 83 adolescents, who were recruited from a Dutch cohort born between the years 1990 and 1993. At the age of 16 and 17y, we determined anthropometric measurements, body composition, physical activity, hours of television use, and self-reported sleep duration. Using linear regression models, we assessed the association between social jetlag, defined as more than a 1-hour difference between the midpoint of sleep during weekdays and weekend days, and body mass index (BMI), body fat percentage, and waist circumference at baseline and after one year. We corrected the analysis for sex, sleep, physical activity, and hours of television use. Results: At age 16y, we observed that social jetlag was highly prevalent, with only 13% of the adolescents reporting no social jetlag (≤1 h), whereas 29% and 58% reported a social jetlag of >1–2 h and ≥2 h. In a cross-sectional analysis, we observed at age 16y a significant higher BMI in the group with no social jetlag, compared to the group with >1- to 2-hour and ≥2-hour social jetlag after adjustment for sex (−0.81 kg/m2, 95% confidence interval = −3.1 to 1.4; and −2.09 kg/m2, 95% confidence interval = −4.1 to −0.1). This association remained significant after correction for the other possible confounders. No significant associations were observed between social jetlag at age 16y and changes in obesity-related characteristics over one year. Conclusion: Our pilot data showed that social jetlag is highly prevalent in adolescents, with social jetlag associated with a lower BMI; however, in this small group, social jetlag was not associated with changes in obesity-related characteristics over time.