Background: Iodine deficiency is a well-established cause of goiter, while the impact of lifestyle factors on goiter development remains underexplored. The study aims to explore the associations between iodine status, lifestyle factors, and the prevalence of goiter among children and adolescents in Zhejiang Province, China. Methods: A cross-sectional survey was conducted in 2022 using a stratified multistage sampling, involving 2261 children aged 6–17. Among these 1562 participants underwent both urinalysis and thyroid ultrasound. Lifestyle factors were assessed through self-reported questionnaires. Results: The prevalence of goiter in the study population was 10.8%. A high urinary iodine concentration (UIC) (>300 μg/L) was significantly associated with a decreased risk of goiter (OR = 0.49, 95%CI: 0.27–0.88). Excessive recreational screen time and a high frequency of dining out were associated with an increased Tvol, while adequate physical activity and sleep were inversely associated with goiter risk, while the combined effect of high UIC and healthy lifestyle showed a protective effect against goiter. Conclusion: Ensuring adequate iodine status and promoting healthy lifestyles are crucial for preventing goiter and enhancing thyroid health in children and adolescents, suggesting that public health strategies should integrate nutritional and lifestyle interventions.