Ginsenoside-Rg1 (G-Rg1) is an agent isolated from Panax ginseng that exerts anti-fibrotic effects; however, the mechanism is still unclear. Herein, we investigated whether G-Rg1 administration can mitigate or reverse unilateral ureteral obstruction (UUO)-induced renal fibrosis by regulating the Klotho/transforming growth factor (TGF)-β1/Smad signaling pathway in rats. Sprague–Dawley male rats were subjected to UUO, and rats in the treatment group were administered G-Rg1 or G-Rg1 plus Klotho short hairpin RNA interference (shRNA), while rats in the control and model groups were administered vehicle for 14 d. Epithelial–mesenchymal transition (EMT) biomarkers and Klotho/TGF-β1 signaling molecules were examined by immunohistochemistry, quantitative real-time PCR and Western blotting. Immunohistochemistry showed that UUO induced increased pro-fibrotic TGF-β1 expression, overexpression of the mesenchymal marker, α-smooth muscle actin (α-SMA), and suppression of the epithelial marker, E-cadherin. Moreover, Western blotting analysis indicated that UUO promoted TGF-β1 and phosphorylated Smad3 (p-Smad3) expression ( p <0.01), but blocked Klotho and Smad7 expression ( p <0.01). After G-Rg1 administration, the UUO-induced TGF-β1 and p-Smad3 expression was suppressed ( p <0.01), whereas the reduced Klotho and Smad7 expression was reversed ( p <0.05), followed by amelioration of the EMT process. Intriguingly, the G-Rg1 effects were largely abrogated by Klotho knockdown. Furthermore, Klotho expression was upregulated by G-Rg1 treatment at the mRNA and protein levels. Our results suggest that G-Rg1 may be beneficial for ameliorating renal fibrosis by targeting Klotho/TGF-β1/Smad signaling in UUO rats.