BACKGROUND: Eggshell quality is a critical determinant of egg product value and consumer preference. Deficient eggshells increase breakage susceptibility, leading to economic losses and reduced marketability. Dietary interventions hold promise for improving eggshell quality. Quercetin, a naturally occurring flavonoid, exhibits diverse biological activities relevant to eggshell formation. These include antioxidant and anti-inflammatory properties, and potential modulation of estrogen levels, which are known to influence eggshell quality. RESULTS: A total of 160 46-week-old laying hens were randomly divided into two groups, with 8 replicates in each group and 10 chickens in each replicate. The control group was fed a corn-soybean meal basal diet, while the experimental group received a basal diet supplemented with 300 mg kg CONCLUSION: This study suggests that compromised eggshell quality might be associated with impaired biomineralization function in the eggshell gland, potentially due to tissue damage. Conversely, dietary quercetin supplementation significantly increased eggshell thickness. We propose a potential mechanism involving the activation of glycine, serine and threonine metabolic pathways, which might enhance the biomineralization capacity and overall health of the eggshell gland. © 2025 Society of Chemical Industry.