Pathogenic Escherichia coli is a common zoonotic pathogen that can cause host diarrhea, edema, and mortality. Tea saponin (Ts) exhibits significant anti-inflammatory and antioxidant properties. However, its potential to mitigate acute intestinal injury caused by pathogenic E. coli remains unclear. This research aimed to investigate the protective effects of Ts against inflammatory pathological damage induced by E. coli and to elucidate the underlying molecular mechanisms. Four experimental groups were established: control, E. coli, E. coli + Ts, and E. coli + MCC950 (a selective NLRP3 inhibitor). Inflammatory pathological damage in the mouse colon was assessed through HE staining, analysis of intestinal barrier markers (ZO-1, Occludin, and Claudin-1), ELISA of inflammatory factors, and analysis of oxidative stress markers. The expression of key apoptosis-related genes and NF-κB/NLRP3 pathway genes was detected using RT-PCR. Immunohistochemistry and Western blot were employed to analyze the expression of apoptosis-related proteins (Bcl-2 and Bax), activated forms of Caspases (Cleaved Caspase-1, Cleaved Caspase-3, Cleaved Caspase-8), tight junction proteins (ZO-1, Occludin, and Claudin-1), and NF-κB/NLRP3 pathway proteins in mouse colon tissues. E. coli infection induced severe histopathological changes and intestinal barrier dysfunction in colon tissues and activated the NF-κB/NLRP3 signaling pathway. This activation significantly increased the expression of pro-apoptotic genes Bax, Caspase-8, and Caspase-3, as well as the levels of their cleaved (active) forms, while markedly decreasing the expression of Bcl-2, thereby promoting apoptosis. Ts treatment notably ameliorated colon pathological injury, effectively regulated the expression of apoptosis-related genes, and significantly suppressed the transcription levels of NF-κB, NLRP3, Caspase-1, IL-1β, IL-18, and TNF-α within the NF-κB/NLRP3 signaling pathway. Furthermore, Ts treatment significantly reduced the protein levels of cleaved Caspase-1, cleaved Caspase-3, and cleaved Caspase-8, and restored the expression of ZO-1, Occludin, and Claudin-1. Ts effectively inhibits inflammatory responses and cell apoptosis induced by E. coli by modulating the NF-κB/NLRP3 signaling pathway, and maintaining intestinal barrier integrity via regulating tight junction proteins, ultimately alleviating colon damage in mouse.