Although chitosan is one of the dietary fibers getting a lot of attention for its potential to reduce obesity markers, its effects on adolescents are still mostly unknown. Researchers sought to examine the impact of chitosan supplementation on cardiometabolic indicators associated with obesity and appetite-related hormones in obese and overweight adolescent girls. A total of 64 overweight and obese adolescents took part in a 12-week randomized clinical trial, with half receiving chitosan supplementation (n=32) and the other 1/2 receiving a placebo as a control (n=32). Hormones associated with appetite and anthropometric measurements, lipid and glucose profiles, and insulin sensitivity were analyzed. A total of 61 people finished the study (31 in the chitosan group and 30 in the placebo group). Chitosan supplementation significantly improved anthropometric indicators of obesity (body weight: − 3.58 ± 2.17 kg, waist circumference: − 5.00 ± 3.11 cm, and body mass index: − 1.61 ± 0.99 kg/m2 and − 0.28 ± 0.19 Z-score), lipid (triglycerides: − 5.67 ± 9.24, total cholesterol: − 14.12 ± 13.34, LDL-C: − 7.18 ± 10.16, and HDL-C: 1.83 ± 4.64 mg/dL) and glycemic markers (insulin: − 5.51 ± 7.52 μIU/mL, fasting blood glucose: − 5.77 ± 6.93 mg/dL, and homeostasis model assessment of insulin resistance: − 0.24 ± 0.44), and appetite-related hormones (adiponectin: 1.69 ± 2.13 ng/dL, leptin − 19.40 ± 16.89, and neuropeptide Y: − 41.96 ± 79.34 ng/dL). Supplementation with chitosan was associated with higher reductions in body weight, BMI (both in kg/m2 and Z-score), waist circumference, and insulin, adiponectin, and leptin compared to the placebo group. According to a P-value less than 0.05, there was statistically significant variation. Adolescents who are overweight or obese can benefit from chitosan supplementation in cardiometabolic parameters (such as anthropometric indicators of obesity and lipid and glycemic markers) and appetite-related hormones (such as adiponectin, leptin, and neuropeptide Y).