Abstract: In this current study, the anti-aging effects and mechanism of action of pectin oligosaccharides from hawthorn (HPOS) on H₂O₂-induced human embryonic lung fibroblast cells were evaluated using the MRC-5 cell line. The effects on cell viability, survival rate, β-galactosidase activity, mitochondrial membrane potential, the content of reactive oxygen species (ROS), antioxidant capacity, and the expression levels of proteins associated with the p53/p21/p16 signaling pathway were evaluated. The findings illustrated that HPOS at a concentration of 0.8 mg/mL could significantly increased cell viability (approximately 16.4%), survival rate (approximately 17.0%), and mitochondrial membrane potential (approximately 284.3%), compared with that in the model group (P<0.01). Furthermore, the proportion of β-galactosidase-positive cells (approximately 66.9%) and fluorescence intensity of ROS (approximately 77.2%) significantly decreased (P<0.01). The superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) contents increased by 72.0% and 50.0%, respectively, compared to that in the model group, whereas the malondialdehyde (MDA) content decreased by 42.6% (P<0.01). HPOS at a concentration of 0.8 mg/mL significantly inhibited p53, p21, and p16 expression in the p53/p21/p16 pathway (P<0.01). Thus, HPOS ameliorates the H₂O₂-induced aging of MRC-5 cells by inhibiting apoptosis and oxidative stress damage along with regulating the p53/p21/p16 pathway, thereby providing a scientific basis for the development of HPOS as a functional food ingredient that acts against aging.