ABSTRACT Psoriasis, a prevalent chronic inflammatory skin disease, substantially impairs patients' quality of life and is frequently linked to numerous systemic comorbidities. We aimed to investigate whether phenotypic age acceleration (PhenoAge‐accel) and obesity synergistically affect the risk of psoriasis. This analysis utilised data from 11 344 participants in the 2003–2006 and 2009–2010 cycles of the National Health and Nutrition Examination Survey (NHANES). Weighted multivariable logistic regression, along with subgroup and sensitivity analyses, was conducted to assess the combined influence of PhenoAge acceleration and body mass index (BMI) on psoriasis risk. At baseline, 307 participants were diagnosed with psoriasis. Both PhenoAge‐accel and elevated body mass index (BMI) were associated with higher risks of psoriasis. After adjusting for potential confounders, compared to those in the BMI < 25 kg/m 2 /PhenoAge‐accel < 0 group, the odds ratios (95% CIs) were 1.07 (0.52–2.20), 1.32 (0.92–1.90), and 2.00 (1.44–2.77) for psoriasis in the BMI < 25 kg/m 2 /PhenoAge‐accel ≥ 0, BMI ≥ 25 kg/m 2 /PhenoAge‐accel < 0, and BMI ≥ 25 kg/m 2 /PhenoAge‐accel ≥ 0 groups, respectively. The results remain robust across a series of subgroups and sensitivity analysis. In conclusion, accelerated phenotypic age and obesity were synergistically associated with an increased risk of psoriasis.