Psoriasis is linked to insulin resistance (IR). Nevertheless, the applicability of the METS-IR index, a new IR evaluation tool, for evaluating changes in insulin sensitivity in psoriasis populations is currently unknown. This study aimed to investigate the relationship between the METS-IR index and psoriasis in a US adult population. This cross-sectional study utilized data from adults aged 20 to 80 years from the U.S. National Health and Nutrition Examination Survey (NHANES) spanning 2003-2006 and 2009-2014. The associations between the METS-IR index and psoriasis were examined using multivariate logistic regression and smoothed curve fitting. Subgroup analyses and interaction tests were conducted to verify the stability of the association within the population. This study included 5,966 participants, of whom 182 had psoriasis. In the fully adjusted model, the METS-IR index was positively associated with psoriasis, showing a 1.7% increase in psoriasis prevalence for each one-unit increase in the METS-IR index (Model 2: OR 1.017, 95% CI 1.006-1.028). Participants in the highest quartile group were 91.9% more likely to develop psoriasis compared to those in the lowest quartile group (OR = 1.919, 95% CI 1.180-3.118). Smooth curve fitting revealed a nonlinear association between the METS-IR index and psoriasis, with an inflection point of 41.675. This positive association was more pronounced in females, non-obese individuals, those with light alcohol consumption, comorbid coronary heart disease and hyperlipidemia, non-hypertensive and non-diabetic individuals. The results of the study suggest that higher METS-IR scores are associated with an increased likelihood of psoriasis among U.S. adults. The METS-IR index is specifically recommended as a clinical indicator for the management and treatment of psoriasis in women, non-obese individuals, light alcohol consumers, individuals with comorbid coronary artery disease andhyperlipidemia, non-hypertensive and non-diabetic individuals. However, Considering the many known and unknown covariates that may be associated with psoriasis and influence theresults of the study, we remain cautious about the results obtained and look forward to the addition of subsequent studies.