A growing body of evidence supports the role of nutrient sensing and metabolism pathways in regulating ageing rate and healthspan, but the diversity of human lifestyles challenges our ability to identify the mechanisms of this age acceleration. Here, we examine how the transition of wild King penguins to zoo husbandry can closely mimic the shift to a Western lifestyle in humans, and shed light on conserved epigenetic changes in responses to sedentary conditions. We show that, just like modern humans, zoo-housed male King penguins experience an extended lifespan, but this comes at the cost of accelerated epigenetic ageing throughout life. This accelerated ageing is associated with differential methylation in key growth and maintenance pathways, including the mTOR and PI3K/Akt networks. Our results demonstrate the conserved link between lifestyle and age acceleration. Such evolutionary evidence may help us to improve risk detection and, ultimately, therapeutics for lifestyle-induced age acceleration in humans.