While ustekinumab has been widely used as an effective biologic for the treatment of chronic plaque psoriasis, no prospective studies have specifically investigated the clinical factors that may influence treatment outcomes with ustekinumab. This post-hoc analysis aimed to identify specific clinical factors that may influence treatment outcomes with ustekinumab in psoriasis patients. In the MARCOPOLO study, 102 Korean patients with moderate to severe psoriasis were analyzed to assess the influence of baseline characteristics as clinical factors on clinical response (improvement in Psoriasis Area and Severity Index by 75%/90% [PASI75/PASI90]) to ustekinumab. In addition, differences in PASI75 and PASI90 responses between the responder group and non-responders were evaluated at weeks 28 and 52. Multiple logistic regression analysis was used to determine adjusted clinical factors predicting treatment outcomes among patient characteristics. At week 28, there was a significant difference in PASI75/PASI90 response based on prior biologic experience, although the difference did not persist at week 52. In addition, after adjusting for the effects of relevant clinical factors, biologic experience was significantly associated with less PASI75 (odds ratio [OR] = 0.14, P = 0.001) and PASI90 (OR = 0.22, P = 0.036) responses at week 28. The presence of comorbidities was higher among non-responders than among PASI75/PASI90 responders at both weeks 28 and 52, but was not statistically significant. Previous biologic use was the only clinical factor predicting less response at week 28, although it did not influence the clinical response after week 52. Further studies are warranted to investigate the association between presence of comorbidities and clinical response.