Objectives: The aim of this study was to evaluate the impact of obesity on the treatment response to secukinumab and drug survival rate in patients with ankylosing spondylitis (AS). Methods: We performed an observational cohort study that included AS patients based on the biological drug database in Turkey (TURKBIO) Registry between 2018 and 2021. The patients were divided into three groups: normal [body mass index (BMI) < 25 kg/m2], overweight (BMI: 25-30 kg/m2), and obese (BMI ≥ 30 kg/m2). Disease activity was evaluated at baseline, 3, 6, and 12 months. Drug retention rates at 12 months were also investigated. Results: There were 166 AS patients using secukinumab (56.6% male, mean age: 44.9 ± 11.6 years). The median follow-up time was 17.2 (3-33.2) months. Forty-eight (28.9%) patients were obese. The mean age was higher in the obese group than in others (P =. 003). There was no statistically significant difference in Bath Ankylosing Spondylitis Disease Activity Index 50, Assessment of SpondyloArthritis international Society 20 (ASAS20), ASAS40, Ankylosing Spondylitis Disease Activity Score (ASDAS) low disease activity, and ASDAS clinically important improvement responses between the three groups at 3, 6, and 12 months, although they were numerically lower in obese patients. Drug retention rates at 12 months were similar in all groups (P >. 05). Conclusions: This study suggested that obesity did not affect secukinumab treatment response and drug retention in AS patients.