INTRODUCTION: Obesity plays a major role in the development of many inflammatory disorders including psoriasis. OBJECTIVES: We aimed to demonstrate how treatment responses change according to body mass index (BMI) among patients with psoriasis. METHODS: In our study, Psoriasis Area and Severity Index (PASI) 75 and PASI 90 responses were assessed at baseline and at months 1 and 3 among patients who received TNF-α inhibitors, ustekinumab, IL-17 blockers, and IL-23 blockers. The same responses were also assessed with methotrexate and acitretin for a comparison group. Analyses were performed retrospectively. RESULTS: The study included 317 patients who received 222 biological and 95 conventional treatments. In the group with BMI ≥30, the proportion of patients who achieved PASI 75 response was 40.0% (N = 26) at month 1 and 55.4% (N = 36) at month 3. The proportion of patients who achieved PASI 90 response was 33.8% (N = 22) at month 1 and 44.6% (N = 29) at month 3 among those receiving biological agents. Improvement was significantly more difficult among obese patients. The proportion of patients who achieved PASI 75 response was 3.6% at month 1 and 25.0% (N = 7) at month 3 among patients receiving conventional systemic treatments. While the presence of joint involvement affected the success of treatment among obese patients with psoriasis, no relationships were found for smoking, the presence of concomitant psychiatric diseases, or the presence of pruritus in psoriasis. CONCLUSIONS: Biological agents were more successful in achieving PASI 75 and PASI 90 responses in both non-obese and obese individuals. Based on our study, among biological agents, IL-17 and IL-23 inhibitors may be more successful among obese individuals, but neither of them shows superiority over the other.