Abstract Background Telomere length is inversely associated with the senescence and aging process. Parallelly, obesity can promote telomere shortening. Evidence suggests that physical activity may promote telomere elongation. Objective This study’s objective is to evaluate the effects of combined exercise training on telomere length in obese women. Design and Methods Twenty pre-menopausal women (BMI 30–40 kg/m², 20–40 years) submitted to combined training (strength and aerobic exercises), but only 13 finished the protocol. Each exercise session lasted 55 min/day, three times a week, throughout 8 weeks. Anthropometric data, body composition, physical performance (Vo_2max), and 8-h fasting blood samples were taken before and after 8 weeks of training. Leukocyte DNA was extracted for telomere length by RT-qPCR reaction, using the 2^−ΔΔCt methodology. Results After the training intervention, significant differences (p < 0.05) were observed in telomere length (respectively before and after, 1.03 ± 0.04 to 1.07 ± 0.04 T/S ratio), fat-free mass (46 ± 7 to 48 ± 5 kg), Vo_2max (35 ± 3 to 38 ± 3 ml/kg/min), and waist circumference (96 ± 8 to 90 ± 6 cm). In addition, an inverse correlation between waist circumference and telomere length was found, before (r = − 0.536, p = 0.017) and after (r = − 0.655, p = 0.015) exercise training. Conclusion Combined exercise promoted leukocyte telomere elongation in obese women. Besides, the data suggested that greater waist circumference may predict shorter telomere length. Clinical Trial Registration ClinicalTrails.gov, NCT03119350. Retrospectively registered on 18 April 2017