The present study investigated the protective effects and possible mechanisms of an ultrafiltration fraction of Sipunculus nudus hydrolysate (UFSH) on cisplatin-induced kidney damage in a mouse model. The results showed that UFSH significantly attenuated cisplatin-induced nephrotoxicity by inhibiting increases in blood urea nitrogen (BUN) and serum creatinine (SCr). Additionally, UFSH treatment significantly alleviated cisplatin-induced renal histopathological changes, such as significant dilation of renal tubules, cast formation, and tubular cell necrosis, as well as tubulointerstitial fibrosis. Moreover, UFSH decreased cisplatin-induced oxidative stress by increasing the activities of antioxidant enzymes SOD and GSH-Px, while reducing the malondialdehyde (MDA) level in the kidney. Furthermore, UFSH significantly inhibited cisplatin-induced increases in inflammatory cytokines, including Interleukin 1-beta (IL-1β), Interleukin-6 (IL-6), and Tumor necrosis factor-alpha (TNF-α). Western blotting revealed that UFSH inhibited the phosphorylation of the inflammation-associated MAPK/NF-κB signaling pathway, lowered the expression of the apoptosis-related protein Bax, and reversed the reduction in the anti-apoptotic Bcl-2 protein. This investigation demonstrated that UFSH can ameliorate cisplatin-induced nephrotoxicity by mitigating oxidative stress, inflammation, and apoptosis.