Extracellular cold-inducible RNA-binding protein (CIRP) functions as damage-associated molecular pattern and has been demonstrated to be responsible in part for the damage occurring after renal ischemia–reperfusion (I/R). A short peptide derived from CIRP, named C23, binds to myeloid differentiation factor 2, a Toll-like receptor 4 coreceptor. We hypothesize that C23 reduces renal ischemia–reperfusion (RIR) injury by blocking CIRP. We observed that pretreatment with C23 significantly decreased the levels of recombinant mouse CIRP-induced tumor necrosis factor-α (TNF-α) in a dose-dependent fashion in cultured macrophages. C57BL/6 mice were subjected to bilateral renal pedicle clamps for 35 min to induce ischemia, followed by reperfusion for 24 h and harvest of blood and renal tissue. C23 peptide (8 mg/kg) or vehicle was injected intraperitoneally at the beginning of reperfusion. Plasma TNF-α, interleukin 1 beta (IL-1β), and IL-6 levels were decreased in C23-treated RIR mice as compared with vehicle-treated mice by 74%, 85%, and 68%, respectively. Expressions of TNF-α and keratinocyte chemoattractant in the kidneys from C23-treated mice were decreased by 55% and 60%, respectively. Expression of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin in the kidney of C23-treated mice were significantly reduced by 46% and 55%, respectively. Renal tissue histological assessments revealed significant reduction in damage score by 44% in C23-treated mice. Finally, a survival study revealed a significant survival advantage with a 70% survival rate in C23 group vs. 37% in vehicle group. Thus, C23 has potential as a novel therapy for the patients suffering from I/R-induced renal injury.