Ocimum basilicum is a valuable plant widely consumed worldwide and considered a rich source of polyphenols. This study examined the impact of the polyphenolic fraction isolated from basil (ObF) on human normal colon epithelial cells and human colorectal adenocarcinoma cells, evaluating its anti-inflammatory and protective activity against oxidative stress. The phytochemical characterization of the fraction was performed using ultra-performance liquid chromatography (UPLC) with a photodiode detector (DAD) and mass spectrometry (MS). UPLC-DAD-MS revealed that ObF predominantly contains caffeic acid derivatives, with rosmarinic acid and chicoric acid being the most abundant. The fraction demonstrated high antioxidant potential, as shown by DPPH assays, along with significant reducing power (FRAP). Furthermore, it prevented the depletion of antioxidant enzymes, including superoxide dismutase and catalase, and decreased malonylodialdehyde (MDA) in induced oxidative stress condition. Additionally, it exhibited a significant protective effect against H2O2-induced cytotoxicity in human normal colon epithelial cells. Although it had no impact on the viability of adenocarcinoma cells, it significantly reduced IL-1β levels in the neoplastic microenvironment. Our study demonstrated that basil polyphenols provide significant health benefits due to their antioxidant and protective activities.