Background <p>This study aimed to assess the association between waist-to-height ratio (WHtR) and the risk of rapid kidney function decline (RKFD) and chronic kidney disease (CKD).</p> Methods <p>This study analyzed 4374 participants from the China Health and Retirement Longitudinal Study (CHARLS). WHtR was calculated as waist circumference (cm) divided by height (cm). RKFD was defined as an annualized estimated glomerular filtration rate (eGFR) decline ≥ 5 mL/min/1.73 m², and CKD as RKFD with eGFR &lt; 60 mL/min/1.73 m² at the final follow-up. Linear mixed-effects models were used to assess the association between baseline WHtR and annual changes of eGFR. Cox proportional hazards models were employed to estimate the association between baseline WHtR and the risks of RKFD and CKD. Restricted cubic spline (RCS) analysis was conducted explored the dose-response relationships.</p> Results <p>Over a mean 3.99-year follow-up, 200 participants (4.57%) developed RKFD, and 66 (1.51%) developed CKD. Each 1-SD increase in WHtR was associated with a greater decline in eGFR (β = -0.242, 95%CI: -0.355 to -0.130) and increased risks of RKFD (HR = 1.298, 95% CI: 1.111 to 1.517) and CKD (HR = 1.518, 95% CI: 1.184 to 1.945) after full adjustment. Compared with the first WHtR quartile group (Q1), the risk of RKFD was significantly increased in Q3 (HR = 1.969, 95%CI: 1.234 to 3.142) and Q4 groups (HR = 2.203, 95%CI: 1.360 to 3.568), whereas the risk of CKD was increased in Q4 group (HR = 3.931, 95%CI: 1.618 to 9.549). RCS analysis demonstrated a positive linear association between baseline WHtR and the incidence of RKFD and CKD (<i>P</i> for nonlinear = 0.403 and 0.492, respectively).</p> Conclusions <p>Elevated WHtR is significantly associated with accelerated eGFR decline and higher risks of RKFD and CKD in middle-aged and older Chinese adults.</p> Clinical trial number <p>Not applicable.</p>