Abstract Aims To investigate sex-specific longitudinal trajectories of various obesity-related measures and blood pressure at the population level and further assess the impact of these trajectories on new-onset atrial fibrillation (AF). Methods and results Participants with ≥2 repeated assessments for various risk factors from the population-based Rotterdam Study were included. Latent class linear mixed models were fitted to identify the potential classes. Cox proportional-hazard models were used to assess the association between risk factors’ trajectories and the risk of new-onset AF, with the most favourable trajectory as reference. Among 7367 participants (mean baseline age: 73 years, 58.8% women), after a median follow-up time of 8.9 years (interquartile range: 5.3–10.4), 769 (11.4%) participants developed new-onset AF. After adjustments for cardiovascular risk factors, persistent-increasing body mass index (BMI) trajectory carried a higher risk for AF [hazard ratio, 95% confidence interval: (1.39; 1.05–1.85) in men and (1.60; 1.19–2.15) in women], compared with the lower-and-stable BMI trajectory. Trajectories of elevated-and-stable waist circumference (WC) in women (1.53; 1.09–2.15) and elevated-and-stable hip circumference (HC) in men (1.83; 1.11–3.03) were associated with incident AF. For systolic blood pressure (SBP), the initially hypertensive trajectory carried the largest risk for AF among women (1.79; 1.21–2.65) and men (1.82; 1.13–2.95). Diastolic blood pressure trajectories were significantly associated with AF risk among women but not among men. Conclusion Longitudinal trajectories of weight, BMI, WC, HC, and SBP were associated with new-onset AF in both men and women. Diastolic blood pressure trajectories were additionally associated with AF in women. Our results highlight the importance of assessing long-term exposure to risk factors for AF prevention among men and women.