Sepsis-associated acute kidney injury (SA-AKI) presents a severe challenge in the elderly due to increasing incidence, high mortality, and the lack of specific effective treatments. Exploring novel and secure preventive and/or therapeutic approaches is critical and urgent. Berberine (BBR), an isoquinoline alkaloid with anti-inflammatory, antioxidant, and immunomodulatory properties, has shown beneficial effects in various kidney diseases. This study examined whether BBR could protect against SA-AKI in aged rats. Sepsis was induced in 26-month-old male Wistar rats by cecal ligation and puncture (CLP), either with or without BBR pretreatment. CLP induction led to SA-AKI, as indicated by elevated serum levels of malondialdehyde, tumor necrosis factor-alpha, urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin (NGAL), along with histopathological features of kidney damage. Key indicators of kidney oxidative stress, mitochondrial dysfunction, apoptosis, and activations of the Toll-like receptor 4/nuclear factor-kappa B (TLR4/NF-κB) signaling, including the nucleotide-binding domain, leucine-rich-containing family, and pyrin domain-containing-3 (NLRP3) inflammasome pathway, were also elevated following CLP induction. BBR pretreatment substantially mitigated these adverse effects, suggesting that it protects against SA-AKI in aged rats by reducing oxidative stress, preserving mitochondrial integrity, and inhibiting key inflammatory pathways. These findings highlight the potential of BBR as a therapeutic agent for managing SA-AKI in elderly populations.