In wild vertebrates, age has a strong influence on individual reproductive performance. Specifically, young parents are less likely to successfully rear offspring relative to older ones because of lower parental skills, lower parental investment or because of a progressive disappearance of lower-quality individuals at young ages (i.e., according to the constraint, restraint and selection hypotheses respectively). Such phenomenon has been extensively studied through reproductive success’ features. However, to better evaluate the influence of age on reproductive performance in species with high reproductive success, assessing also the quality of developmental conditions and offspring phenotype appears crucial. While it is practically difficult to follow an offspring during its entire life, several proxies of nestlings’ quality can be useful to assess the ability of young to survive and recruit into the population (i.e., body condition, corticosterone levels, and telomere length). By sampling chicks reared by known-aged mothers, we specifically investigated the influence of maternal age on offspring quality in two long-lived seabird species, the Black-browed Albatross (Thalassarche melanophrys) and the Snow Petrel (Pagodroma nivea). In both species, maternal age is correlated to proxies of offspring quality. More precisely, older individuals provide better parental cares to their offspring. In the light of the three age-related improvement of reproductive performance hypotheses, our results suggest that maternal age can affect offspring phenotype with potential long-term consequences.