The association between the atherogenic index of plasma (AIP) and urine albumin-to-creatinine ratio (UACR) has not been fully elucidated in large-scale populations. This study aimed to systematically examine the association between AIP and elevated UACR in Chinese urban adults. UACR was categorized as normal (UACR < 30 mg/g) and albuminuria (UACR ≥ 30 mg/g), and participants were divided into quartiles according to AIP distribution. Multivariable logistic regression models were used to evaluate the association between AIP and elevated UACR after adjustment for potential confounders. Higher AIP quartiles were significantly and positively associated with increased odds of albuminuria. In the fully adjusted model, the odds ratios for elevated UACR were 1.304 (95% CI: 1.196, 1.422), 1.475 (95% CI: 1.355, 1.607), and 1.815 (95% CI: 1.668, 1.975) for the second, third, and fourth AIP quartiles, respectively, compared with the lowest quartile (all p < 0.001). Subgroup analyses indicated that this association was more pronounced among individuals younger than 60 years and those not using lipid-lowering medications. These findings suggest that elevated AIP level is independently associated with increased UACR in the Chinese urban population, particularly in younger individuals not receiving lipid-lowering therapy.