This study investigated the effects of dietary supplementation with grape pomace powder (GP) on the performance, egg quality and hatchability, and blood biochemistry of quails (Coturnix coturnix japonica). A total of 200 quails (323.90 ± 1.991 g body weight) were randomly divided into four treatment groups, with five replicates of ten birds each. The treatments involved dietary supplementation with GP at 0% (0GP), 1% (1GP), 2% (2GP), and 4% (4GP) of the basal diet for eight weeks. The results indicated that GP significantly affected feed intake, egg production, and egg weight. The 1GP and 2GP treatments had higher egg production and a better feed conversion ratio (FCR) than the other treatments. The lowest egg production and poorest FCR in the study were in the 4GP group. Feed intakes and egg weights were lower in the supplemented groups than in the 0GP group. The 1GP, 2GP, and 4GP groups had higher eggshell breaking strength, Haugh unit, and egg albumen index values than the 0GP group. Plasma total cholesterol and high-density lipoprotein cholesterol concentrations in all GP-supplemented groups were lower than in the 0GP quails. The effects of GP supplementation on chick live weight and early embryonic mortality were significant, with GP supplementation considerably reducing early embryonic deaths compared to the 0GP group. In conclusion, this study showed that adding up to 2% GP to quails’ diets had no negative effects on live performance, improved some egg quality traits, decreased early embryonic deaths, and may have helped reduce total lipid and cholesterol levels.