The study examined the association between baseline levels of intact fibroblast growth factor 23 (iFGF-23) and progression of chronic kidney disease (CKD) in 602 adult patients with mild to moderate CKD at 11 Indian hospitals over a median of 5.3 years. iFGF-23 levels were measured by plasma two-site ELISA. The primary endpoint was serious adverse renal events (MAKE: renal failure, ≥50% decline in eGFR, or death from renal causes), which occurred in 266 (49.3%) participants; 223 (41.3%) achieved renal failure, 211 (43.5%) ≥50% decline in eGFR, and 66 (11.0%) died. In unadjusted and age-sex-adjusted Cox models, iFGF-23 was significantly associated with MAKE (SHR 1.23, 95% CI 1.02–1.47, p=0.027), renal failure (SHR 1.28, 95% CI 1.04–1.58, p=0.02) and all-cause mortality (HR 1.83, 95% CI 0.839–3.989, p=0.02). In a fully adjusted model with clinical risk factors, no association was statistically significant. Thus, iFGF-23 levels did not provide independent prognostic value, and routine testing has limited benefit.