The effects of supplementing a basal diet with 2 levels of an essential oil mixture and an antibiotic on the growth, laying traits, and egg hatching characteristics of broiler breeders were examined in this study. Nine hundred sixty female and 128 male breeders at an age of 1 d old were randomly allocated to 16 replicates (i.e., 4 replicates of 4 dietary treatments) in a floor pen trial. Two levels of an essential oil mixture (EOM; i.e., 24 and 48 mg of EOM/kg of diet) and an antibiotic (i.e., 10 mg of avilamycin/kg of diet) were added to the basal starter, grower, and laying diets from 0 to 45 wk of age. Daily feed allocations were adjusted to produce a target BW and egg production rate of the breeders throughout the experimental period. The BW of the males and females were determined at 12, 21, and 45 wk of age. Livability during the growing and laying period was not affected by the dietary treatments. The fertility and hatchability of total eggs set were positively affected by the supplementation of the EOM in the diet (P < 0.01). The hen-day egg production, hatching egg weight, settable egg ratio, hatching of fertile eggs, extra large egg rate, and proportion of chick weight to egg weight were not affected significantly. The higher level of EOM (48 mg/kg) added to the diet led to the hatching of the heaviest chickens; the lower level of EOM (24 mg/kg) and antibiotic treatments led to the hatching of the intermediate weight chickens, followed by the control treatment (P < 0.01). Hens given the lower level of EOM in their diets produced a higher number of settable eggs and chicks as compared with those of other treatments, whereas hens fed the control diet yielded the lowest total settable eggs and chicks throughout the experimental laying period (P < 0.05). The results of this study showed that supplementing diets with EOM improved fertility, the hatchability of total eggs set, total settable eggs, total chicks, and the chick weight of broiler breeders.